Conflict of absl library compiled by bazel

[zengguofei]

I use bazel to integrate opentelemetry-cpp, and there is already an absl library in my project; I try to use the macro definition "HAVE_ABSEIL", but it does not work, it is still connected to the absl library of opentelemery.

I had to change the bazel compilation inside opentelemetry-cpp; change the absl dependency to my local library. I hope this dependency can provide good guidelines for external libraries.

[owent]

This's the same problem as #1065 .

[lalitb]

Duplicate of #1065
Let's continue to track this in another issue, and close this.