Fix flood warning when combining XR with cinemachine brain

[fcoulombe]

case 1074030 is having issues of flood wanrings complaining about cinemachine brain conflicting with xr camera.
This is due to ShouldUseVRFieldOfView() returning true in Camera::SetVerticalFieldOfView because we have a vr device.
URP 10.0.0 fixed this using #22 by setting disableLegacyRenderer to true
to force a VRDeviceToXRDisplaySetup::TeardownShimFuncs(*this);. This is so there's no function override left in
the shim table when calling UninstallVRDeviceShims from ProcessPendingTextureRequestsSynchronized which will finally
call ShimTeardownIfActive(); to finally reset completely the legacy render device s_LegacyDevice = NULL;.which allows
ShouldUseVRFieldOfView() to return false and therefore not throw a warning in Camera::SetVerticalFieldOfView.

Please read the Contributing guide before making a PR.

• Read the Graphics repository & Yamato FAQ.

Checklist for PR maker

• Have you added a backport label (if needed)? For example, the need-backport-* label. After you backport the PR, the label changes to backported-*.
• Have you updated the changelog? Each package has a CHANGELOG.md file.
• Have you updated or added the documentation for your PR? When you add a new feature, change a property name, or change the behavior of a feature, it's best practice to include related documentation changes in the same PR. If you do add documentation, make sure to add the relevant Graphics Docs team member as a reviewer of the PR. If you are not sure which person to add, see the Docs team contacts sheet.
• Have you added a graphic test for your PR (if needed)? When you add a new feature, or discover a bug that tests don't cover, please add a graphic test.

---

Purpose of this PR

Why is this PR needed, what hard problem is it solving/fixing?

---

Testing status

Describe what manual/automated tests were performed for this PR

---

Comments to reviewers

Notes for the reviewers you have assigned.