Dotfiles should check for a case-insensitive value of "true" for "fallback

[jdreed]

When determining whether or not to run zwgc on the dialups, the dotfiles check for "fallback: true" as the output of "zctl show fallback".

However, a value of "TRUE" is also valid and will cause zwgc to fallback to ttymode, but will fail our test. We should test case-insensitively.

[jdreed]

Fixed in r24393

[jdreed]

Moved to production today, and mail sent to ops to ask for an update on the dialups