Restyle fix: Remove cmake cache files after copying to container build directory

[restyled-io]

A duplicate of #2325 with additional commits that automatically address
incorrect style, created by Restyled.

Since the original Pull Request was opened as a fork in a contributor's
repository, we are unable to create a Pull Request branching from it with only
the style fixes.

The following Restylers made fixes:

• shellharden

To incorporate these changes, you can either:

1. Merge this Pull Request instead of the original, or

2. Ask your contributor to locally incorporate these commits and push them to
   the original Pull Request

   Expand for example instructions

   ```console
   git remote add upstream https://github.com/TokTok/c-toxcore.git
   git fetch upstream pull/<this PR number>/head
   git merge --ff-only FETCH_HEAD
   git push
   ```
   

NOTE: As work continues on the original Pull Request, this process will
re-run and update (force-push) this Pull Request with updated style fixes as
necessary. If the style is fixed manually at any point (i.e. this process finds
no fixes to make), this Pull Request will be closed automatically.

Sorry if this was unexpected. To disable it, see our documentation.

---

This change is 

[codecov]

Codecov Report

Merging #2342 (3738f47) into master (7dfa935) will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2342      +/-   ##
==========================================
+ Coverage   78.06%   78.12%   +0.05%     
==========================================
  Files         140      140              
  Lines       31053    31053              
==========================================
+ Hits        24243    24260      +17     
+ Misses       6810     6793      -17     

Impacted Files	Coverage Δ
auto_tests/group_invite_test.c	98.44% <0.00%> (-0.78%)	⬇️
toxcore/TCP_server.c	78.58% <0.00%> (-0.19%)	⬇️
toxcore/onion_client.c	89.76% <0.00%> (-0.12%)	⬇️
toxcore/DHT.c	85.08% <0.00%> (-0.08%)	⬇️
toxcore/net_crypto.c	87.13% <0.00%> (-0.08%)	⬇️
toxcore/group_chats.c	69.33% <0.00%> (+0.33%)	⬆️
auto_tests/group_sync_test.c	85.11% <0.00%> (+0.46%)	⬆️
toxcore/TCP_client.c	84.07% <0.00%> (+0.70%)	⬆️
toxcore/group_moderation.c	81.70% <0.00%> (+1.54%)	⬆️

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