Removes ReadAccountMapEntry

[brooksprumo]

Problem

See #34786 for background.

We want to limit the use of ReadAccountMapEntry, from AccountsIndex, everywhere. Ultimately removing it once there are no more uses.

And now, there are no more uses!

Summary of Changes

Each is its own commit, to make it easier to step through:

• Remove get()
• Remove AccountIndexGetResult
• Remove ReadAccountMapEntry

Fixes #34786

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.7%. Comparing base (6ee3bb9) to head (90b45ad).
Report is 6 commits behind head on master.

❗ Current head 90b45ad differs from pull request most recent head d02488b. Consider uploading reports for the commit d02488b to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #35351   +/-   ##
=======================================
  Coverage    81.7%    81.7%           
=======================================
  Files         834      834           
  Lines      224299   224310   +11     
=======================================
+ Hits       183361   183376   +15     
+ Misses      40938    40934    -4     

[jeffwashington]

what about cargo.toml?

[brooksprumo]

what about cargo.toml?

Removing the ouroboros dependency will be done in #35355.

[jeffwashington]

yay!

[HaoranYi]

Let's have a party to celebrate 🥳