This pull request updates conditional compilation directives in two test
files to reflect additional platforms where the tests are known to fail.
These changes help ensure that problematic tests are properly excluded
on all relevant platforms.

Test exclusion updates:

* In `Issue18751.cs`, the test is now excluded on both iOS and Catalyst
with an updated related issue reference.
* In `Issue18896.cs`, the test exclusion is expanded to include Android,
alongside iOS, Catalyst, and Windows, with updated related issue
references.

Issue: #33507

### Description of Change

Add support to build internal device tests and uitests pipelines 


This pull request updates the device test pipelines and Helix
configuration to better distinguish between internal and public builds.
The changes introduce separate build and test pools for internal and
public environments, add support for passing Helix access tokens for
internal runs, and update queue and argument selection logic to ensure
tests are sent to the appropriate Helix queues. Additionally, pipeline
timeouts are increased to accommodate longer-running jobs.

Key changes include:

**Pipeline Pool and Token Configuration:**

* Added separate build and test pool parameters for internal and public
environments in both `ci-device-tests.yml` and `ci-uitests.yml`,
enabling the pipelines to select the correct pools based on whether the
build is internal or public.
[[1]](diffhunk://#diff-3c01e959fbddcc83fed139e6855a1fb2211a82deff79904912c021d96e433d2bR50-R79)
[[2]](diffhunk://#diff-3c01e959fbddcc83fed139e6855a1fb2211a82deff79904912c021d96e433d2bL62-R94)
[[3]](diffhunk://#diff-f0d1c4172dd9c907f376bbf9165bb7866553b059e26c8519320d65b9d4e673e3L63-R137)
* Introduced logic to include the Helix access token variable group for
internal builds, and added a `HelixAccessToken` parameter to device test
stages.
[[1]](diffhunk://#diff-3c01e959fbddcc83fed139e6855a1fb2211a82deff79904912c021d96e433d2bR50-R79)
[[2]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bR49-R51)

**Helix Queue and Argument Selection:**

* Updated `helix_xharness.proj` to select different Helix target queues
for internal and public builds, using the new `HelixInternal` property.
* Modified `stage-device-tests.yml` to pass the `HelixInternal` property
and `HelixAccessToken` to Helix jobs based on whether the build is
internal or public, ensuring tests are routed to the correct queues.
[[1]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bL148-R155)
[[2]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bL198-R209)
[[3]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bL246-R261)
[[4]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bL349-R368)

**Pipeline Timeout Adjustments:**

* Increased job timeouts for device test build and run stages to allow
for longer test execution, reducing the risk of premature timeouts.
[[1]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bL74-R77)
[[2]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bL179-R186)
[[3]](diffhunk://#diff-1701856ca68fbbb9e8a01b54e77e4f16271e630dee939e507f9133e4b9e7f46bL275-R290)

**Pipeline Template Usage:**

* Updated stage and job templates to use the new pool parameters and
conditional logic, ensuring the correct pools and tokens are applied
throughout the pipelines.
[[1]](diffhunk://#diff-3c01e959fbddcc83fed139e6855a1fb2211a82deff79904912c021d96e433d2bL85-R119)
[[2]](diffhunk://#diff-3c01e959fbddcc83fed139e6855a1fb2211a82deff79904912c021d96e433d2bL105-R141)
[[3]](diffhunk://#diff-f0d1c4172dd9c907f376bbf9165bb7866553b059e26c8519320d65b9d4e673e3L106-R161)

These changes collectively improve the reliability and security of the
device test pipelines by ensuring internal and public builds use the
appropriate resources and credentials.

# Conflicts:
#	eng/pipelines/ci-device-tests.yml