ci: qemuv8: preventively avoid "no space left on device" errors

During my testing of build.git PR 731 ("optee_rust_examples_ext: Fix Rust
toolchain conflicts"), I noticed that the "no space left on device"
error was triggered yet again (obviously due to more size being taken on
the disk by the Rust toolchain and the OP-TEE Rust examples).

Therefore, preventively apply the same fix as for other jobs. This way
the CI should pass when 731 is merged.

Link: https://github.com/OP-TEE/build
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Sumit Garg <sumit.garg@linaro.org>

.github/workflows/ci.yml

@@ -268,6 +268,8 @@ jobs:
     runs-on: ubuntu-latest
     container: jforissier/optee_os_ci:qemuv8_check2
     steps:
+      - name: Remove /__t/*
+        run: rm -rf /__t/*
       - name: Restore build cache
         uses: actions/cache@v3
         with:
@@ -371,6 +373,8 @@ jobs:
     runs-on: ubuntu-latest
     container: jforissier/optee_os_ci:qemuv8_check2
     steps:
+      - name: Remove /__t/*
+        run: rm -rf /__t/*
       - name: Restore build cache
         uses: actions/cache@v3
         with: