Stale user app data in analytics when the VM service connection changes

[elliette]

When the VM service connection changes, DevTools calls setupUserApplicationDimensions.

However, because _userApplicationDimensionsComputed was set to true after the first VM service connection, the dimensions are not updated for the new connection.

devtools/packages/devtools_app/lib/src/shared/analytics/_analytics_web.dart

Lines 849 to 857 in 92913e2

	void setupUserApplicationDimensions() {
	if (serviceConnection.serviceManager.connectedApp != null &&
	!_userApplicationDimensionsComputed &&
	!_computingUserApplicationDimensions) {
	_computingUserApplicationDimensions = true;
	_computeUserApplicationCustomGTagData();
	_userApplicationDimensionsComputed = true;
	}
	}