ci/vs2019: Convert mesa_build.ps1 to using PowerShell 7 && operator

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16934>

.gitlab-ci/windows/mesa_build.ps1

@@ -59,15 +59,9 @@ meson `
 -Dwarning_level=2 `
 -Dzlib:warning_level=1 `
 -Dlibelf:warning_level=1 `
-$sourcedir
-
-if ($?) {
-  meson install --skip-subprojects
-}
-
-if ($?) {
-  meson test --num-processes 32
-}
+$sourcedir && `
+meson install --skip-subprojects && `
+meson test --num-processes 32
 
 $buildstatus = $?
 Pop-Location