[HTTP Client] Reduce the frequency of creating and destroying background threads in HTTP Client. #3189
Description
Is your feature request related to a problem?
The HTTP Client may frequently create and destroy threads when it's not always busy, which will cost a lot of resource.
Could we keep the background thread for a while and destroy only when it's free for some more time? Just like the background thread in OTLP file exporter.
I can take this, if it's accepted.
Describe the solution you'd like
Wait a longer time to destroy HTTP Client's background thread.
Additional context
I can casually try to optimize the issue in #3172.