remove httpclient caching from DefaultHttpClientFactory

[liga-oz]

HttpClient caching in DefaultHttpClientFactory does not add any value to the way how it is used across the other library modules, where the created httpClient is stored as a field variable in the corresponding classes and reused from there.

Moreover, as the service configuration is loaded once per app start, extending a cache with a cache key that include a clientid, a certificate thumbprint and implementing also a cache eviction logic would not have any impact on key rotation without app restart and therefore caching the http connections would not bring anything.