test: fix os-release check for Ubuntu in SEA test

For example, my `/etc/os-release` file begins with
```
PRETTY_NAME="Ubuntu 22.04.2 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
```
so in order to match the regexp here, the `/m` flag is necessary.
PR-URL: #46838
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: addaleax

test/parallel/test-single-executable-application.js

@@ -41,7 +41,7 @@ if (process.config.variables.want_separate_host_toolset !== 0)
 if(process.platform==='linux'){
 try{
 constosReleaseText=readFileSync('/etc/os-release',{encoding: 'utf-8'});
-if(!/^NAME="Ubuntu"/.test(osReleaseText)){
+if(!/^NAME="Ubuntu"/m.test(osReleaseText)){
 thrownewError('Not Ubuntu.');
 }
 }catch{