TT#111150 Do not override the while build flags on unit-test workflow

We need to pass these on through environment otherwise we are overriding
the whole build flags.

Change-Id: I3fd856af2624f84afe73427dfb359e8bfc3acaa8
Fixes: commit f791bf03f9

.github/workflows/unit-tests.yml

@@ -24,4 +24,4 @@ jobs:
 
       - name: Run unit tests with sanitizers enabled
         run: |
-          make CFLAGS="$FLAGS" LDFLAGS="$FLAGS" check
+          CFLAGS="$FLAGS" LDFLAGS="$FLAGS" make check