Update intellisense package version to RC2

[safern]

cc: @carlossanlop

[Dotnet-GitSync-Bot]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[safern]

/backport to release/5.0-rc2

[github-actions]

Started backporting to release/5.0-rc2: https://github.com/dotnet/runtime/actions/runs/254597501

[safern]

We're going to hold this PR in case we need one more update for the intellisense package and merge on the 28th.

[safern]

/backport to release/5.0-rc2

[github-actions]

Started backporting to release/5.0-rc2: https://github.com/dotnet/runtime/actions/runs/270043462

[github-actions]

@safern backporting to release/5.0-rc2 failed, the patch most likely resulted in conflicts:

$ git am --3way --ignore-whitespace --keep-non-patch changes.patch

Applying: Update intellisense package version to RC2
error: sha1 information is lacking or useless (eng/Versions.props).
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Update intellisense package version to RC2
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!