fix: add --timeout-multiplier=2 to meson test

meson test rest_integration_test can sometimes run longer, let's
see if --timeout-multiplier=2 can resolve this problem

Author: zhjwpku

.github/workflows/test.yml

@@ -137,4 +137,4 @@ jobs:
           meson compile -C builddir
       - name: Test Iceberg
         run: |
-          meson test -C builddir
+          meson test -C builddir --timeout-multiplier=2