-p silently fails if parameter is an invalid plugin

• a detailed description of the bug or problem you are having

  When using --disable-plugin-autoload, some plugins, eg pytest-recording, are not picked unless the parameter to -p is the entry point, not the module name.
  However, this fails silently -- using the module name doesn't cause any warnings from pytest.

  In particular, this can be detected by checking if pytest accepts the command line flags defined by these plugins -- with -p pytest_recording, --block_network isn't accepted, but with -p recording it is.

• output of pip list from the virtual environment you are using

Package          Version
---------------- -------
iniconfig        2.3.0
packaging        25.0
pip              25.3
pluggy           1.6.0
Pygments         2.19.2
pytest           9.0.2
pytest-recording 0.13.4
PyYAML           6.0.3
vcrpy            8.1.1
wrapt            2.0.1

• pytest and operating system versions: pytest-9.0.2, Arch Linux

• minimal example if possible

  With

Start by reproducing the issue with pytest --disable-plugin-autoload -p pytest_recording and -p recording, comparing plugin registration and command-line option handling. Trace pytest's plugin-loading entry point and related tests for -p parameters. Done means an invalid plugin parameter is no longer silently accepted and the behavior is covered by a regression test.