Fix Windows Script Tests: pre-assign concatenated here-string before Set-Content

[Copilot]

The "Windows Script Tests" CI job was failing with DryRun failures: 1 — MockRun FAILED: jenv_setup.ps1 JEnv choice resolution - A positional parameter cannot be found that accepts argument '+'.

Root Cause

PowerShell treats a here-string (@'...'@) as a single, complete token when used as a cmdlet argument. When the mock jenv.cmd was written as:

Set-Content -LiteralPath ... -Value @'
...static lines...
'@ + "  echo jdk-21.0.12.8-hotspot $mockJdkForBatch`r`n" + @'
...more static lines...
'@

PowerShell consumed the first @'...'@ as the -Value argument, then encountered + on the closing '@ line and tried to bind it as a positional argument to Set-Content — which has no such parameter. The error only surfaced on Windows because the Linux path takes the else branch (plain here-string, no concatenation).

Fix

• scripts/windows/run_tests.ps1: Assign the concatenated content to $jenvCmdContent before passing it to Set-Content. In assignment context, + is correctly parsed as the string concatenation operator.

$jenvCmdContent = @'
...
'@ + "  echo jdk-21.0.12.8-hotspot $mockJdkForBatch`r`n" + @'
...
'@
Set-Content -LiteralPath (Join-Path $mockRoot "jenv.cmd") -Value $jenvCmdContent