[improve][test] Fixed flakiness of SaslAuthenticateTest.testSaslOnlyAuthFirstStage

[storm-08]

Fixes #xyz

Motivation

The test SaslAuthenticateTest.testSaslOnlyAuthFirstStage is flaky due to a strict assertion on cache size. When the loop inserting entries runs longer than the configured 50ms expiry, early entries may get evicted, causing the test to fail sometimes.

Modifications

• SaslAuthenticateTest : Modified the assertion - now it asserts that sum of evicted entries and entries currently in cache equals to 10 i.e. it will also take in account of the expired entries.
• AuthenticationProviderSasl : Enabled accumulation of stats from which count of evicted entries can be fetched

Verifying this change

• Make sure that the change passes the CI checks.

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

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• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

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