fix(ota): Magic byte check fails with encrypted firmware

[me-no-dev]

The check was running before firmware was decrypted, so it fails.
Changes run the check only when unencrypted firmware is being uploaded.

Fixes: #9850

[github-actions]

	Messages
📖	🎉 Good Job! All checks are passing!

👋 Hello me-no-dev, we appreciate your contribution to this project!

---

Click to see more instructions ...

This automated output is generated by the PR linter DangerJS, which checks if your Pull Request meets the project's requirements and helps you fix potential issues.

DangerJS is triggered with each push event to a Pull Request and modify the contents of this comment.

Please consider the following:
- Danger mainly focuses on the PR structure and formatting and can't understand the meaning behind your code or changes.
- Danger is not a substitute for human code reviews; it's still important to request a code review from your colleagues.
- To manually retry these Danger checks, please navigate to the Actions tab and re-run last Danger workflow.

Review and merge process you can expect ...

We do welcome contributions in the form of bug reports, feature requests and pull requests.

1. An internal issue has been created for the PR, we assign it to the relevant engineer.
2. They review the PR and either approve it or ask you for changes or clarifications.
3. Once the GitHub PR is approved we do the final review, collect approvals from core owners and make sure all the automated tests are passing.
- At this point we may do some adjustments to the proposed change, or extend it by adding tests or documentation.
4. If the change is approved and passes the tests it is merged into the default branch.

Generated by 🚫 dangerJS against b102cb6

[github-actions]

Memory usage test (comparing PR against master branch)

The table below shows the summary of memory usage change (decrease - increase) in bytes and percentage for each target.

Memory	FLASH [bytes]		FLASH [%]		RAM [bytes]		RAM [%]
Target	DEC	INC	DEC	INC	DEC	INC	DEC	INC
ESP32S3	0	0	0.00	0.00	0	0	0.00	0.00
ESP32S2	0	0	0.00	0.00	0	0	0.00	0.00
ESP32C3	0	0	0.00	0.00	0	0	0.00	0.00
ESP32C6	0	0	0.00	0.00	0	0	0.00	0.00
ESP32H2	0	0	0.00	0.00	0	0	0.00	0.00
ESP32	0	0	0.00	0.00	0	0	0.00	0.00

Click to expand the detailed deltas report [usage change in BYTES]

Target	ESP32S3		ESP32S2		ESP32C3		ESP32C6		ESP32H2		ESP32
Example	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM
Update/examples/AWS_S3_OTA_Update	-	-	-	-	-	-	-	-	-	-	-	-
Update/examples/HTTPS_OTA_Update	-	-	-	-	-	-	-	-	-	-	-	-
Update/examples/HTTP_Client_AES_OTA_Update	-	-	-	-	-	-	-	-	-	-	-	-
Update/examples/HTTP_Server_AES_OTA_Update	-	-	-	-	-	-	-	-	-	-	-	-
Update/examples/OTAWebUpdater	-	-	-	-	-	-	-	-	-	-	-	-
Update/examples/SD_Update	-	-	-	-	-	-	-	-	-	-	-	-

[github-actions]

Test Results

 56 files   56 suites   5m 12s ⏱️
 21 tests  21 ✅ 0 💤 0 ❌
135 runs  135 ✅ 0 💤 0 ❌

Results for commit b102cb6.

♻️ This comment has been updated with latest results.