Don't use auto-inferred name in as.data.table.matrix under new rule

[MichaelChirico]

For #7145. This probably doesn't fix everything; I've only checked on {tidytable}.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.50%. Comparing base (4cf9a70) to head (1acf5da).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7149   +/-   ##
=======================================
  Coverage   98.50%   98.50%           
=======================================
  Files          81       81           
  Lines       15017    15019    +2     
=======================================
+ Hits        14793    14795    +2     
  Misses        224      224           

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[github-actions]

No obvious timing issues in HEAD=as-dt-matrix-v1

Generated via commit 1acf5da

Download link for the artifact containing the test results: ↓ atime-results.zip

Task	Duration
R setup and installing dependencies	4 minutes and 42 seconds
Installing different package versions	9 minutes and 5 seconds
Running and plotting the test cases	2 minutes and 26 seconds

[tdhock]

great, thanks, let's see how this works.