Fix xliff tasks being loaded even when not needed

[bekir-ozturk]

Fixes an issue created by #8233

After the change above, Xliff tasks package is now loaded even in the cases where it isn't needed.
This causes issues with some repos (and likely others that aren't listed below):

• [main] Update dependencies from dotnet/arcade aspnetcore#38839
• [main] Update dependencies from dotnet/arcade winforms#6263

The dotnet/templating and dotnet/test-templates repos seem to be working fine and are not affected by this bug.

The fix is to correct the usage of flags so that Xliff tasks package will only be loaded when needed.
Tested on local clone of winforms repo. Xliff tasks are no longer referenced unless needed.

To double check:

• The right tests are in and and the right validation has happened. Guidance: https://github.com/dotnet/core-eng/tree/master/Documentation/Validation

[MattGal]

This seems fine, but do note that the setting is opt-out (true by default) if that matters.

arcade/src/Microsoft.DotNet.Arcade.Sdk/tools/DefaultVersions.props

Line 36 in f08de58

<UsingToolXliff Condition="'$(UsingToolXliff)' == ''">true</UsingToolXliff>

[JamesNK]

Ready to merge? It would be good to get aspnetcore and ef dependency updates unblocked.

[bekir-ozturk]

The issue is now fixed and the dependency update was merged into aspnetcore repo.

[sunandabalu]

We are seeing the xliff failures in our repo with the latest arcade update PR - https://github.com/dotnet/upgrade-assistant/pull/970/checks?check_run_id=4464498289. Assuming the next arcade update should have the fix? @dotnet/dnceng

[riarenas]

Yes. the next update will have this fix.