chore: support to get ca-key file when enabling tls

[wangyelei]

Some databases require mutual authentication, which means both the client and server must verify each other’s identity. In such cases, you need a CA (Certificate Authority) key file and a CA certificate to issue client certificates

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 60.10%. Comparing base (fbd2ea0) to head (940b62d).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/controller/plan/tls.go	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8840      +/-   ##
==========================================
+ Coverage   60.06%   60.10%   +0.03%     
==========================================
  Files         382      382              
  Lines       46123    46128       +5     
==========================================
+ Hits        27704    27724      +20     
+ Misses      15748    15726      -22     
- Partials     2671     2678       +7     

Flag	Coverage Δ
unittests	60.10% <88.88%> (+0.03%)	⬆️

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