Make sure there's no await between clearing and filling the environment

[Tyriar]

This is causing the warning icon to show up more.

vscode-python/src/client/terminals/envCollectionActivation/service.ts

Lines 224 to 226 in b4aa112

	// Clear any previously set env vars from collection
	envVarCollection.clear();
	const deactivate = await this.terminalDeactivateService.getScriptLocation(shell, resource);

[eleanorjboyd]

looping in Karthik since the terminal environment items on the core python extension related to terminal deactivation is under his domain