Revert "Initial pass on TPM-backed disk encryption support (#46457)" (#48101)

This reverts commit 19ba1ed787. (PR:
https://github.com/fleetdm/fleet/pull/46457.)

# Checklist for submitter

## Testing

- [x] QA'd all new/changed functionality manually

## fleetd/orbit/Fleet Desktop

- [x] Verified compatibility with the latest released version of Fleet
(see [Must
rule](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/workflows/fleetd-development-and-release-strategy.md))
- [x] If the change applies to only one platform, confirmed that
`runtime.GOOS` is used as needed to isolate changes
- [x] Verified that fleetd runs on macOS, Linux and Windows
- [x] Verified auto-update works from the released version of component
to the new version (see [tools/tuf/test](../tools/tuf/test/README.md))


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Changes**
* Unified the disk encryption prompt on TPM-backed Linux hosts to
display standard passphrase entry dialogs consistently, removing
specialized messaging previously shown for recovery key scenarios.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

orbit/changes/46457-tpm-backed-luks-recovery-key-prompt

@@ -1 +0,0 @@
-- Updated the Fleet Desktop disk encryption prompt on TPM-backed Linux hosts (e.g., Ubuntu 23.10+) to ask for the disk recovery key saved during installation, instead of a LUKS passphrase.