winsvc: Fix bug where service accidentally stops after starting

[daipom]

Which issue(s) this PR fixes:
This fixes a bug of #4909.

What this PR does / why we need it:
After 53bcd3c (#4909), the service accidentally stops after starting, without stopping the supervisor and workers.

Docs Changes:
Not needed.

Release Note:
The same as the title.
Not needed for v1.19 because #4909 has not been released in the normal version yet.

[daipom]

I do not understand why this trace log is marked as Error.
However, it does not seem to affect the test.
I have confirmed that if there is a matching log, the test enters the if statement as expected, and the test fails.

https://github.com/fluent/fluentd/actions/runs/14992579391/job/42119227188?pr=4954#step:5:97

Error: DEBUG: 26+ if ( >>>> Select-String -Path $_ -Pattern "[warn]", "[error]", "[fatal]" -SimpleMatch -Quiet) {

[daipom]

The fails of Windows tests with Ruby 3.2 and 3.3 have nothing to do with this fix.

[daipom]

I do not understand why this trace log is marked as Error. However, it does not seem to affect the test. I have confirmed that if there is a matching log, the test enters the if statement as expected, and the test fails.

https://github.com/fluent/fluentd/actions/runs/14992579391/job/42119227188?pr=4954#step:5:97

Error: DEBUG: 26+ if ( >>>> Select-String -Path $_ -Pattern "[warn]", "[error]", "[fatal]" -SimpleMatch -Quiet) {

It appears that GitHub responds to the [error] string, and it has nothing to do with the PowerShell process.
We can ignore this.

https://github.com/daipom/test-ci/actions/runs/14994067883/job/42124023183

$ErrorActionPreference = "Stop"
Set-PSDebug -Trace 1

"error" | Out-Null
"[error]" | Out-Null
"error" | Out-Null

DEBUG:    4+  >>>> "error" | Out-Null

Error: DEBUG:    5+  >>>> "[error]" | Out-Null

DEBUG:    6+  >>>> "error" | Out-Null

DEBUG:    3+ if ( >>>> (Test-Path -LiteralPath variable:\LASTEXITCODE)) { exit $LASTEXITCODE }

[ashie]

LGTM

[daipom]

Thanks for your review!