server: Split TestTLS

[dveeden]

What problem does this PR solve?

Issue Number: #26947

Problem Summary: TestTLS can take more than 3 minutes. Splitting this helps to identify what part is problematic

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• morgo
• tiancaiamao

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[dveeden]

/run-check_dev_2

[zhouqiang-cl]

/run-check_dev_2

[dveeden]

/cc @tiancaiamao @morgo

[morgo]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: effb301

[zhouqiang-cl]

Seems TestTLSAuto still take much time
[2021-08-17T02:30:32.622Z] PASS: tidb_test.go:874: tidbTestSerialSuite.TestTLSAuto 6.148s

in ci https://ci.pingcap.net/blue/organizations/jenkins/tidb_ghpr_check_2/detail/tidb_ghpr_check_2/26519/pipeline

[dveeden]

Seems TestTLSAuto still take much time
[2021-08-17T02:30:32.622Z] PASS: tidb_test.go:874: tidbTestSerialSuite.TestTLSAuto 6.148s

in ci https://ci.pingcap.net/blue/organizations/jenkins/tidb_ghpr_check_2/detail/tidb_ghpr_check_2/26519/pipeline

@zhouqiang-cl Yes, that's why #26947 is not closed yet. This is due to the RSA key size and the issue has a proposed solution.