--remote-execution global option should likely disable remote execution environments

[Eric-Arellano]

It is very useful to have the flag --remote-execution as a quick CLI toggle for RE. For example, when you're on a plane, you want to disable RE without having to rewrite all of your BUILD files to change the environment= they are set to.

I tried to implement that logic inside our rules that set up the Platform, CompleteEnvironmentVars, and ProcessConfigFromEnvironment: ca3c581. But I realized this was not a valid approach. While that commit "fixes" those 3 types to use the local environment, the env vars and executable search paths would still be coming from the remote_environment target, rather than the local_environment target, which is an error.

Instead, the fallback must live one level higher, in our rule that determines which environment name should be used via "matcher" logic:

pants/src/python/pants/core/util_rules/environments.py

Lines 336 to 339 in 8923ea2

	@rule
	async def resolve_environment_name(
	request: EnvironmentNameRequest, environments_subsystem: EnvironmentsSubsystem
	) -> EnvironmentName: