ABFS: Fixing Test Script Bug and Some Known test Failures in ABFS Test Suite

Test Script used by ABFS to validate changes has following two issues:

1. When there are a lot of test failures or when error message of any failing test becomes very large, the regex used today to filter test results does not work as expected and fails to report all the failing tests.
   To resolve this, we have come up with new regex that will only target one line test names for reporting them into aggregated test results.
2. While running the test suite for different combinations of Auth type and account type, we add the combination specific configs first and then include the account specific configs in core-site.xml file. This will override the combination specific configs like auth type if the same config is present in account specific config file. To avoid this, we will first include the account specific configs and then add the combination specific configs.

Due to above bug in test script, some test failures in ABFS were not getting our attention. This PR also targets to resolve them. Following are the tests fixed:

1. ITestAzureBlobFileSystemAppend.testCloseOfDataBlockOnAppendComplete(): It was failing only when append blobs were enabled. In case of append blobs we were not closing the active block on outputstrea,close() due to which block.close() was not getting called and assertions around it were failing. Fixed by updating the production code to close the active block on flush.
2. ITestAzureBlobFileSystemAuthorization: Tests in this class works with an existing remote filesystem instead of creating a new file system instance. For this they require file system configured in account settings using following config: "fs.contract.test.fs.abfs". Tests weref ailing with NPE when this config was not present. Updated code to skip thsi test if required config is not present.
3. ITestAbfsClient.testListPathWithValueGreaterThanServerMaximum(): Test was failing Intermittently only for HNS enabled accounts. Test wants to assert that client.listPath() does not return more objects than what is configured in maxListResults. Assertions should be that number of objects returned could be less than expected as server might end up returning even lesser due to partition splits along with a continuation token.
4. ITestGetNameSpaceEnabled.testGetIsNamespaceEnabledWhenConfigIsTrue(): Fail when "fs.azure.test.namespace.enabled" config is missing. Ignore the test if config is missing.
5. ITestGetNameSpaceEnabled.testGetIsNamespaceEnabledWhenConfigIsFalse(): Fail when "fs.azure.test.namespace.enabled" config is missing. Ignore the test if config is missing.
6. ITestGetNameSpaceEnabled.testNonXNSAccount(): Fail when "fs.azure.test.namespace.enabled" config is missing. Ignore the test if config is missing.
7. ITestAbfsStreamStatistics.testAbfsStreamOps: Fails when "fs.azure.test.appendblob.enabled" is set to true. Test wanted to assert that number of read operations can be more in case of append blobs as compared to normal blob because of automatic flush. It could be same as that of normal blob as well.
8. ITestAzureBlobFileSystemCheckAccess.testCheckAccessForAccountWithoutNS: Fails for FNS Account only when following config is present:  fs.azure.account.hns.enabled". Failure is because test wants to assert that when driver does not know if the account is HNS enabled or not it makes a server call and fails. But above config is letting driver know the account type and skipping the head call. Remove these configs from the test specific configurations and not from the account settings file.
9. ITestAbfsTerasort.test_120_terasort: Fails with OAuth on HNS account. Failure is because of identity mismatch. OAuth uses service principle OID as owner of the resources whereas Shared Key uses local system identities. Fix is to set configs that will allow overwrite of OID to localidentity. This will require a new config to be set by user that specify which OID has to be substituted. OAuth by default uses Superuser Identity, so same needs to be configured to be overwritten as well.
   New test config: "fs.azure.account.oauth2.client.service.principal.object.id"
10. ITestExponentialRetryPolicy.testThrottlingIntercept: Fails with SharedKey only. Test was using a dummy account to create a new instance of AbfsConfiguration and for that dummy account, SharedKey was not configured. Fix is to Add non-account specific SharedKey in accountconfigs.
11. ITestAzureBlobFileSystemLease:testTwoCreate(): Fail when "fs.azure.test.namespace.enabled" config is missing. Fix is to Ignore the test if config is missing.
12. ITestAzureBlobFileSystemChecksum.testAppendWithChecksumAtDifferentOffsets: Test fails with append blob enabled because position parameter in append call was passed wrong. Fixed the test to work with append blobs.