planner: introduce new cost formula for IndexLookup

[qw4990]

What problem does this PR solve?

Issue Number: ref #35240

Problem Summary: introduce new cost formula for IndexLookup

What is changed and how it works?

Introduce new cost formula for IndexLookup: accumulate the real double-read cost:

1. doubleReadCost = numDoubleReadTasks * SeekFactor;
2. numDoubleReadTasks is based on a magic number distRatio=40, doubleReadRows / IndexBatchSize * distRatio.

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• time-and-fate
• xuyifangreeneyes

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[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/e971f0928cb6ef36319054b0f3629c171495d40e

[qw4990]

/run-unit-test

[qw4990]

/merge

[ti-chi-bot]

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

Commit hash: e971f09

[qw4990]

/run-unit-test

[sre-bot]

TiDB MergeCI notify

🔴 Bad News! [1] CI still failing after this pr merged.
These failed integration tests don't seem to be introduced by the current PR.

CI Name	Result	Duration	Compare with Parent commit
idc-jenkins-ci-tidb/integration-common-test	🔴 failed 2, success 9, total 11	22 min	Existing failure
idc-jenkins-ci/integration-cdc-test	🟢 all 34 tests passed	33 min	Existing passed
idc-jenkins-ci-tidb/common-test	🟢 all 12 tests passed	10 min	Existing passed
idc-jenkins-ci-tidb/tics-test	🟢 all 1 tests passed	6 min 34 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-2	🟢 all 28 tests passed	6 min 3 sec	Existing passed
idc-jenkins-ci-tidb/integration-ddl-test	🟢 all 6 tests passed	5 min 13 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-1	🟢 all 26 tests passed	4 min 16 sec	Existing passed
idc-jenkins-ci-tidb/mybatis-test	🟢 all 1 tests passed	2 min 55 sec	Existing passed
idc-jenkins-ci-tidb/integration-compatibility-test	🟢 all 1 tests passed	2 min 52 sec	Existing passed
idc-jenkins-ci-tidb/plugin-test	🟢 build success, plugin test success	4min	Existing passed