Change keys of the discovery flags such that they conform to the convention

[GuptaManan100]

Description

Now that we have started making more and more flags as dynamic configurations in viper, we have settled on the default convention for this. We are using the same flag name as the key name in viper. The discovery flags that were added previously didn't follow this convention and have been changed to do so.

This PR is built on top of #17419 because it required some testing changes setup that that PR adds.

Related Issue(s)

Checklist

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[vitess-bot]

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[deepthi]

Some minor naming changes are needed. rest LGTM.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.65%. Comparing base (9383943) to head (6a0b2cc).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17430      +/-   ##
==========================================
- Coverage   67.67%   67.65%   -0.03%     
==========================================
  Files        1583     1584       +1     
  Lines      254363   254386      +23     
==========================================
- Hits       172140   172094      -46     
- Misses      82223    82292      +69     

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