Remove check for interactive mode in labs installer (#3709)

## Changes

If this condition evaluates to true, it returns `(nil, nil)` and leads
to a panic further along in the code. The check for an interactive
terminal is done earlier than necessary and can be removed altogether.
The `askWorkspaceProfile` function also checks for an interactive
terminal and returns an error if there isn't one.

We mark Git Bash as a terminal where prompting is not supported (see
#1069).

Fixes #3597.

## Tests

Manually confirmed the installer no longer panics in Git Bash on
Windows.

Author: pietern

cmd/labs/project/installer.go

@@ -168,10 +168,6 @@ func (i *installer) recordVersion(ctx context.Context) error {
 }
 
 func (i *installer) login(ctx context.Context) (*databricks.WorkspaceClient, error) {
-	if !cmdio.IsPromptSupported(ctx) {
-		log.Debugf(ctx, "Skipping workspace profile prompts in non-interactive mode")
-		return nil, nil
-	}
 	cfg, err := i.metaEntrypoint(ctx).validLogin(i.cmd)
 	if errors.Is(err, ErrNoLoginConfig) {
 		cfg, err = i.Installer.envAwareConfig(ctx)