chore(ci): add more replicas

[WenyXu]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

What's changed and what's your intention?

As the title said, add more etcd, frontend, meta replicas for test.

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR requires documentation updates.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.15%. Comparing base (418090b) to head (c01c6f2).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4015      +/-   ##
==========================================
- Coverage   85.44%   85.15%   -0.29%     
==========================================
  Files         980      980              
  Lines      170112   170112              
==========================================
- Hits       145352   144860     -492     
- Misses      24760    25252     +492     

[fengjiachun]

LGTM