KVStore: Temporarily disable reusing read index history

[CalvinNeo]

What problem does this PR solve?

Issue Number: close #8845

Problem Summary:

According to #8845, we have to temporarily disable this mechanism before we find a way to address the current problem.

After this pr, we will expect more read index request being handled and processed by both TiFlash and TiKV. There could be some performance regressions, due to:

1. More requests may heavy the burden of TiKV and TiFlash.
2. Some single read index request could potentially processed slower, because it can't reuse history anymore.

What is changed and how it works?

Check List

Tests

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

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

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[CalvinNeo]

/hold wait for another several round of regression tests

[CalvinNeo]

[CalvinNeo]

This PR does not help