fix: bugs related to merge scan

[waynexia]

I hereby agree to the terms of the GreptimeDB CLA

What's changed and what's your intention?

Fix some bugs related distributed query

• prevent TypeConversionRule from convert types other than timestamp and boolean
• prevent optimizer from optimize plan after MergeScan
• use the schema from optimized plan as the output schema of MergeScan
• optimize input plan if the MergeScan is executed only in frontend

The error log:

MySQL [(none)]>  SELECT SUM(-1) FROM numbers WHERE number=-1;
ERROR 1815 (HY000): Failed to execute query: SELECT SUM(-1) FROM numbers WHERE number=-1, source: Failed to execute logical plan, source: Failure during query execution, source: Fail to create physical plan: Internal error: The type of UInt32 Eq Int64 of binary physical should be same. This was likely caused by a bug in DataFusion's code and we would welcome that you file an bug report in our issue tracker

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.

Refer to a related PR or issue link (optional)

[evenyag]

Please fix the title.

[evenyag]

If it works not only on your machine ......

[v0y4g3r]

LGTM

[codecov]

Codecov Report

Merging #2118 (6e10d78) into develop (7210b35) will decrease coverage by 0.43%.
Report is 13 commits behind head on develop.
The diff coverage is 97.36%.

@@             Coverage Diff             @@
##           develop    #2118      +/-   ##
===========================================
- Coverage    84.94%   84.51%   -0.43%     
===========================================
  Files          687      687              
  Lines       108052   108596     +544     
===========================================
- Hits         91786    91784       -2     
- Misses       16266    16812     +546