scripts: unit-test: Constrain test setups to current project

self.package now reflects the top-level meson project name. Using this,
prevent incorrect propagation of configuration into subprojects using
the usual meson scope syntax.

Further, now that we're using the scope syntax, meson outputs a
different error message:

```
$ meson test --setup=stdplus:__likely_not_a_setup__ -C build __likely_not_a_test__
Unknown test setup 'stdplus:__likely_not_a_setup__'.
```

Adjust the regex that performs the setup error test.

Change-Id: Ia15c0406323f025fff318cb1c1e4a92605d19c96
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/scripts/unit-test.py b/scripts/unit-test.py
index 461e49a..e678a8c 100755
--- a/scripts/unit-test.py
+++ b/scripts/unit-test.py
@@ -991,7 +991,7 @@
                         "-C",
                         "build",
                         "--setup",
-                        setup,
+                        "{}:{}".format(self.package, setup),
                         "__likely_not_a_test__",
                     ],
                     stderr=subprocess.STDOUT,
@@ -999,7 +999,7 @@
         except CalledProcessError as e:
             output = e.output
         output = output.decode("utf-8")
-        return not re.search("Test setup .* not found from project", output)
+        return not re.search("Unknown test setup '[^']+'[.]", output)
 
     def _maybe_valgrind(self):
         """
@@ -1021,7 +1021,7 @@
                     "build",
                     "--print-errorlogs",
                     "--setup",
-                    "valgrind",
+                    "{}:valgrind".format(self.package),
                 )
             else:
                 check_call_cmd(