Uses mmap for names in tiered storage

[brooksprumo]

Problem

Mmap variables are used inside tiered storage in many places. Sometimes they are called mmap and sometimes they are called map. Since map already has a common, different meaning, we should (1) be consistent, and (2) prefer mmap.

Summary of Changes

Renames map to mmap.

[yhchiang-sol]

Thank you! This is also one thing in my mind. Thanks for picking this up!

[codecov]

Codecov Report

Merging #34127 (4588e51) into master (32993b2) will increase coverage by 0.0%.
Report is 1357 commits behind head on master.
The diff coverage is 90.9%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #34127      +/-   ##
==========================================
  Coverage    81.8%    81.9%              
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  Files         766      818      +52     
  Lines      209077   219939   +10862     
==========================================
+ Hits       171130   180207    +9077     
- Misses      37947    39732    +1785