[JAVA][FEIGN] Put back hardcoded HTTP Client but without the performance issue created in 8484. This is fix for 21187

[sushma3690]

Fixes #21187

This fix takes care of the performance issue created in #8484 as mentioned in detail in #21085

Context:

1. [JAVA][FEIGN] Implement unit tests for java-feign client #8484 introduced new client with every invocation of APIClient which caused application throttling in basic performance tests
2. [JAVA][FEIGN] Removing hardcoded HTTP Client which is causing performance issues #21085 reverted the above change and hence removed the problem
3. [BUG] [feign-java] default client changed; okhttp vs httpclient5 are now the same? #21187 showed us that there are now consumers leveraging [JAVA][FEIGN] Implement unit tests for java-feign client #8484 already and either want the behavior back or make it explicit that there is no support for httpclient5

This PR fixes all the above problems - has support for all the clients and removes the performance bottlenecks.
Those who need customization can anyway pass custom client through Feign.Builder.

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[sushma3690]

@wing328 / @bbdouglas / @sreeshas / @jfiala / @lukoyanov / @cbornet / @jeff9finger / @karismann / @Zomzog / @lwlee2608 / @martin-mfg please help review.

[cubic-dev-ai]

No issues found across 5 files

[wing328]

thanks for the fix

if no feedback from anyone, i'll get it merged over the weekend.