Revert changes to DEP enrollment flow

[gillespi314]

Reverts #20162 and #20355 per QA findings

[gillespi314]

Down migrations to be applied manually to dogfood and QA environments:

ALTER TABLE mdm_idp_accounts DROP INDEX idx_mdm_idp_accounts_host_uuid;

ALTER TABLE mdm_idp_accounts DROP COLUMN host_uuid;

ALTER TABLE mdm_idp_accounts DROP COLUMN fleet_enroll_ref;

DELETE FROM migration_status_tables WHERE version_id IN(20240709175341, 20240710152744)

[mna]

Backend revert LGTM.

[lucasmrod]

We should send a message to #help-engineering so that devs know that this change might break their local setups.

[lucasmrod]

Changes look good (assuming it's an exact revert).

[codecov]

Codecov Report

Attention: Patch coverage is 47.05882% with 18 lines in your changes missing coverage. Please review.

Project coverage is 37.20%. Comparing base (b4b4498) to head (b2e1106).
Report is 4 commits behind head on main.

Files	Patch %	Lines
server/mock/datastore_mock.go	0.00%	6 Missing ⚠️
server/service/osquery_utils/queries.go	0.00%	3 Missing and 1 partial ⚠️
server/datastore/mysql/hosts.go	62.50%	2 Missing and 1 partial ⚠️
server/service/apple_mdm.go	60.00%	1 Missing and 1 partial ⚠️
server/worker/apple_mdm.go	66.66%	2 Missing ⚠️
server/datastore/mysql/apple_mdm.go	80.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #20506       +/-   ##
===========================================
- Coverage   55.12%   37.20%   -17.93%     
===========================================
  Files        1426     1423        -3     
  Lines      134052   133761      -291     
  Branches     3218     3216        -2     
===========================================
- Hits        73900    49764    -24136     
- Misses      54125    79508    +25383     
+ Partials     6027     4489     -1538     

Flag	Coverage Δ
backend	35.77% <47.05%> (-19.48%)	⬇️

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