I decided to try something.
I copied the files from C:\ProgramData\Microsoft\AndroidSDK\25\tools into cmdline-tool directory, but that didn't help.
I tried the files from C:\Program Files (x86)\Android\android-sdk\tools, and copied those into the cmdline-tools directory, and the messages went away, and the emulator was recognized in the debugger.
C:\Program Files (x86)\Android\android-sdk\emulator\emulator.EXE -no-boot-anim -avd pixel_2_r_11_0_-_api_30 -prop monodroid.avdname=pixel_2_r_11_0_-_api_30
Emulator pixel_2_r_11_0_-_api_30 cannot be started.
That was quite a short moment of hope. :(
Edit
So I had to manually start the emulator. then keep choosing to wait rather than close. Then debug the project, and it works.

I guess then, the workaround is to copy the files from the tools directory into the cmdline-tools directory for now, until Microsoft Visual Studio SDK Manager can place them in that folder in the future.

