fix(cluster/operation): extract the correct java's version field

[9547]

What problem does this PR solve?

The old jdk8's version as below:

# java -version
openjdk version "1.8.0_265"
OpenJDK Runtime Environment (build 1.8.0_265-b01)
OpenJDK 64-Bit Server VM (build 25.265-b01, mixed mode)

But the newly Java(11 or higher)'s version as below:

# java -version
openjdk version "11.0.8" 2020-07-14
OpenJDK Runtime Environment (build 11.0.8+10-post-Debian-1deb10u1)
OpenJDK 64-Bit Server VM (build 11.0.8+10-post-Debian-1deb10u1, mixed mode, sharing)

And as TiSpark 用户指南 | PingCAP Docs saied, TiSpark needs JDK 1.8+

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[ti-srebot]

This issue contains Chinese, please use English.

[9547]

/cc @AstroProfundis

[AstroProfundis]

I remember I've tested that only Jave 1.8 is working as the Spark we bundled is quite old. @marsishandsome could you confirm the JRE version requirement?

[lucklove]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• lucklove

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[lucklove]

/merge

[ti-chi-bot]

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

Commit hash: cbc0867

[ti-chi-bot]

@9547: Your PR has out-of-dated, I have automatically updated it for you.

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