[BUG] `/eng/scripts/Update-Mgmt-CI.ps1` doesn't work correctly under non-Windows

[archerzz]

Library name and version

eng ci script

Describe the bug

See this PR: #47422 which contains a lot of unexpected changes to ci.mgmt.yml, basically a repetitive content is inserted. The root cause is probably in

azure-sdk-for-net/eng/scripts/Update-Mgmt-CI.ps1

Line 59 in 529e8fa

$ciContent = $ciContent -replace "(?s)(paths:\r\n(\s+)include:\r\n(?:\s+-[^\r\n]*\r\n)*(?:\s+-\s+$relServiceDir/?\r\n)(?:\s+-[^\r\n]*\r\n)*)(?!\s+exclude:)", "`$1`$2exclude:`r`n`$2- $relPackageDir`r`n"

which doesn't work correctly under non-Windows environment.

Expected behavior

/eng/scripts/Update-Mgmt-CI.ps1 should work correctly under non-Windows environment.

Actual behavior

Due to regex matching failure, a repetitive content will be inserted in ci.mgmt.yml of each sdk.

Reproduction Steps

Run /eng/scripts/Update-Mgmt-CI.ps1 under non-Windows environment

Environment

No response

[archerzz]

This issue has shown up in our CI as well. Check this spec PR: https://github.com/Azure/azure-rest-api-specs-pr/pull/20571

The bot has generated malformed content in the corresponding PR: https://github.com/azure-sdk/azure-sdk-for-net-pr/pull/2414