[fix](storage): Ensure TOO_MANY_VERSION error is correctly detected and triggered in RowsetBuilder

[0AyanamiRei]

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:
This PR fixes a bug in RowsetBuilder::check_tablet_version_count where the TOO_MANY_VERSION error was not triggered due to being masked by the memory limit check. In the original logic, if the tablet version count did not exceed max_version_config - 100 or the memory usage exceeded the soft limit (GlobalMemoryArbitrator::is_exceed_soft_mem_limit), the method returned Status::OK() prematurely, bypassing the version count check against max_tablet_version_num. This caused the TOO_MANY_VERSION error to be suppressed, leading to incorrect behavior in version limit enforcement and failing regression tests (e.g., too_many_versions_detection). The fix reorders the logic to prioritize the version count check, ensuring TOO_MANY_VERSION is triggered when version_count > max_tablet_version_num. Additionally, a new FETCH_MEMORY_EXCEEDED error is introduced for memory shortage cases to improve error clarity.

Release note

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Check List (For Author)

• Test

  • Regression test
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  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
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• Behavior changed:

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  • Yes.

• Does this need documentation?

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  • Yes.

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[Thearas]

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