mgr/orchestrator: fix encrypted flag handling in orch daemon add osd

mgr/orchestrator: fix encrypted flag handling in orch daemon add osd

The current implementation incorrectly parses this `encrypted` flag as a string rather than a boolean value.
This leads to unintended behavior causing an LVM encryption layer to be created regardless of whether `encrypted=True` or `encrypted=False` is passed.
The only way to prevent this behavior is by omitting the `encrypted` flag entirely.
This change prevents potential errors, aligning the behavior with user expectations.

Fixes: https://tracker.ceph.com/issues/67372
Signed-off-by: Yonatan Zaken <yonatan.zaken@gmail.com>
(cherry picked from commit 42721c03ee6f2c47a20dfb4d40af4f7f7afe6113)