Instead of pointing to Python.org use the new python extension install command

[IanMatthewHuff]

Fixes #10696

• Pull request represents a single change (i.e. not fixing disparate/unrelated things in a single PR).
• Title summarizes what is changing.
• Has a news entry file (remember to thank yourself!).
• Appropriate comments and documentation strings in the code.
• Has sufficient logging.
• Has telemetry for feature-requests.
• Unit tests & system/integration tests are added/updated.
• Test plan is updated as appropriate.
• package-lock.json has been regenerated by running npm install (if dependencies have changed).

[IanMatthewHuff]

pythonNotInstalled was unused (plus the function names here didn't match the nls names) so removed the NonMarkdown one and did a rename.

[codecov-commenter]

Codecov Report

Merging #10750 (d17d0ad) into main (5e0e77a) will decrease coverage by 0%.
The diff coverage is 0%.

@@          Coverage Diff           @@
##            main   #10750   +/-   ##
======================================
- Coverage     62%      62%   -1%     
======================================
  Files        476      476           
  Lines      32985    32983    -2     
  Branches    5356     5356           
======================================
- Hits       20756    20735   -21     
- Misses     10253    10261    +8     
- Partials    1976     1987   +11     

Impacted Files	Coverage Δ
...ollers/commands/installPythonControllerCommands.ts	57% <0%> (ø)
src/platform/common/utils/localize.ts	75% <ø> (+<1%)	⬆️
src/platform/debugger/debugger.ts	66% <0%> (-12%)	⬇️
src/notebooks/debugger/debuggingManagerBase.ts	69% <0%> (-7%)	⬇️
src/kernels/installer/productInstaller.node.ts	74% <0%> (-5%)	⬇️
...rnels/raw/finder/localKernelSpecFinderBase.node.ts	81% <0%> (-3%)	⬇️
src/kernels/execution/cellExecutionQueue.ts	81% <0%> (-2%)	⬇️
src/platform/common/process/baseDaemon.node.ts	50% <0%> (-2%)	⬇️
src/kernels/execution/cellExecution.ts	71% <0%> (-2%)	⬇️
src/kernels/kernelDependencyService.node.ts	85% <0%> (-1%)	⬇️
... and 6 more