Remove notes about ITuple changes(#7633) from v6.2.0-preview.1 updates.

[stknohg]

PR Summary

Related #8070, #8077.

The notes of #7633 was already included in PowerShell Core 6.1.0 stable.

Note: We also must update Release notes of v6.2.0-preview.1.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Change is not breaking
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: to the beginning of the title and remove the prefix when the PR is ready.
• User-facing changes
  • Not Applicable
  • OR
  • User-facing Documentation needed
    • Issue filed - Issue link:
• Testing - New and feature
  • Not Applicable or can only be tested interactively
  • OR
  • Make sure you've added a new test if existing tests do not effectively test the code changed
    • Add [feature] if the change is significant or affects feature tests

[anmenaga]

Changing change log is probably too late.
But we can manually update description of the v6.2.0-preview.1 release.

[iSazonov]

The update is useful for next release.

[iSazonov]

Reopen PR to restart CIs.

[stknohg]

Currently, WIP is required.
Do I need to do something?

[iSazonov]

@SteveL-MSFT @TravisEz13 Can we fix the change log issue?

[SteveL-MSFT]

If the changelog is wrong, we should fix it. We can ignore the WIP bot since it's clear it doesn't apply to this PR.

[iSazonov]

@TravisEz13 Please merge the PR.