gha: buildkit: make checks more readable

GitHub uses these parameters to construct a name; removing the ./ prefix
to make them more readable (and add them back where it's used)

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 0760c6f4e1)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.github/workflows/buildkit.yml

@@ -52,11 +52,11 @@ jobs:
       fail-fast: false
       matrix:
         pkg:
-          - ./client
-          - ./cmd/buildctl
-          - ./solver
-          - ./frontend
-          - ./frontend/dockerfile
+          - client
+          - cmd/buildctl
+          - solver
+          - frontend
+          - frontend/dockerfile
         typ:
           - integration
     steps:
@@ -107,6 +107,6 @@ jobs:
           CONTEXT: "."
           TEST_DOCKERD: "1"
           TEST_DOCKERD_BINARY: "./build/moby/binary-daemon/dockerd"
-          TESTPKGS: "${{ matrix.pkg }}"
+          TESTPKGS: "./${{ matrix.pkg }}"
           TESTFLAGS: "-v --parallel=1 --timeout=30m --run=//worker=dockerd$"
         working-directory: buildkit