Move clang builds to use lld

Clang builds are currently complaining about a missing LLVMGold plugin.
```
/usr/bin/ld: /usr/lib/llvm-20/bin/../lib/LLVMgold.so: error loading plugin: /usr/lib/llvm-20/bin/../lib/LLVMgold.so: cannot open shared object file: No such file or directory
```

In the past this was because the plugin got moved into an llvm-linkers
apt package unintentionally.  The move to the new ubuntu seems to have
forced this to be a problem again, and adding the llvm-linkers package
doesn't fix it like it had in the past.

While compiling with clang and linking with ld should work fine, it's
likely simpler to run the whole llvm toolchain when doing clang builds.
Therefore, move meson clang builds to LLD.

Change-Id: Ibf952a31695061a958cb437d74ea4b264ce96aaa
Signed-off-by: Ed Tanous <etanous@nvidia.com>
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index 389a313..8def57c 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -916,7 +916,8 @@
 RUN apt-get install -y \
         clang-20 \
         clang-format-20 \
-        clang-tidy-20
+        clang-tidy-20 \
+        lld-20
 
 RUN update-alternatives --install /usr/bin/clang clang /usr/bin/clang-20 1000 \
   --slave /usr/bin/clang++ clang++ /usr/bin/clang++-20 \
@@ -924,7 +925,8 @@
   --slave /usr/bin/clang-format clang-format /usr/bin/clang-format-20 \
   --slave /usr/bin/run-clang-tidy run-clang-tidy.py \
         /usr/bin/run-clang-tidy-20 \
-  --slave /usr/bin/scan-build scan-build /usr/bin/scan-build-20
+  --slave /usr/bin/scan-build scan-build /usr/bin/scan-build-20 \
+  --slave /usr/bin/lld lld /usr/bin/lld-20
 
 """