Executable metadata missing for some executables on hosts with a large number of executables

[Gandem]

What happened?

Opened as a follow-up to #244

On hosts where the profiler sees as large number of executables (more than 16384 as of 0dac5dd), the executables cache in the reporter will be eventually full, and the least recently used entries will be evicted. Currently, there's no control or guarantee as to when those entries will be re-inserted in that cache.

As a consequence, mappings for these executable's frames will no longer contain the file name field and gnu build id attribute (both are extracted from executable metadata).

Potential fixes

There was initial discussion in #244 (comment) on ways we could fix this, with caveats raised on the reporter API #244 (comment)

Opening this issue for longer term discussion on this.