[WOOMOB-2574] Disable FedEx support locally

[irfano]

Description

Fixes WOOMOB-2574

Disables FedEx in the Android shipping labels flow behind a temporary feature flag.
This hides FedEx in both the package carrier tabs and the shipping rates flow while the mobile support remains turned off.

Slack discussion:

Test Steps

1. Open an order that can be used to create a shipping label (The site should be connected to staging server).
2. Start the shipping label flow.
3. Go to the package selection screen.
4. Open the Carrier tab.
5. Confirm FedEx is not shown in the carrier list.
6. Continue to the shipping rates step.
7. Confirm FedEx rates are not shown.

Images/gif

Before	After

• I have considered if this change warrants release notes and have added them to RELEASE-NOTES.txt if necessary. Use the "[Internal]" label for non-user-facing changes.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce Android
	Platform	📱 Mobile
	Flavor	Jalapeno
	Build Type	Debug
	Build Number	736
	Version	24.4-rc-1
	Application ID	com.woocommerce.android.prealpha
	Commit	6844355
	Installation URL	2e4flhhpt3sl8

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 39.62%. Comparing base (3674aff) to head (6844355).

Files with missing lines	Patch %	Lines
...els/packages/datasource/ObserveShippingPackages.kt	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##              trunk   #15587   +/-   ##
=========================================
  Coverage     39.62%   39.62%           
- Complexity    11336    11338    +2     
=========================================
  Files          2260     2260           
  Lines        130597   130605    +8     
  Branches      18302    18304    +2     
=========================================
+ Hits          51753    51758    +5     
- Misses        73555    73557    +2     
- Partials       5289     5290    +1     

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[AdamGrzybkowski]

Looks good! One question though - couldn't the backend simply filter out FedEx until its ready? 🤔

[AdamGrzybkowski]

❓ Any reasons for not taking advantage of the new unified feature flag handling and setting the local value to true while disabling the feature remotely? Is there any benefit of having it done in a way that requires an extra app update?

[AdamGrzybkowski]

@irfano Should this PR target 24.4?