Bug/fix tls error default fallback

[Akshay2191]

Currently, if TLS credentials are misconfigured or unreadable, we silently fall back to insecure credentials without notifying the user.

With this change, if TLS is configured but the certificates are invalid, we log an error and do not add any transport credentials, ensuring the user is aware that their TLS configuration is not working.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.12%. Comparing base (acd199e) to head (524e736).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1655      +/-   ##
==========================================
+ Coverage   83.57%   85.12%   +1.54%     
==========================================
  Files         105      105              
  Lines       16370    13697    -2673     
==========================================
- Hits        13682    11659    -2023     
+ Misses       2173     1524     -649     
+ Partials      515      514       -1     

Files with missing lines	Coverage Δ
internal/grpc/grpc.go	81.41% <100.00%> (-0.21%)	⬇️

... and 101 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update acd199e...524e736. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.