lgtm: drop the TMPDIR/meson workaround

The underlying issue seems to be fixed, so let's drop the now obsolete
workarounds.

Introduced in 65be7042a8

.lgtm.yml

@@ -9,16 +9,6 @@ extraction:
         - libfdisk-dev
         - libp11-kit-dev
         - libssl-dev
-    before_index:
-      # /tmp has `noexec` set in the LGTM infra which breaks meson's
-      # compilation checks. Let's temporarily override TMPDIR to /var/tmp which
-      # should work as expected
-      # See: https://discuss.lgtm.com/t/meson-fails-to-determine-sizes-of-basic-data-types/2639
-      - export TMPDIR=/var/tmp
-    index:
-      build_command:
-        - meson build
-        - ninja -C build
   python:
     python_setup:
       version: 3