[ToolChains][FreeBSD] Set default Linker to LLD for FreeBSD (#190596)

When the linker is specified as ld, toolchain applies special handling
by invoking (triple)-ld instead of resolving ld via standard PATH
lookup. This causes GNU ld installed via the system package manager to
take the precedence (since (triple)-ld appears earlier in the search
path), effectively overriding ld.lld.

As a result, we set the default Linker on FreeBSD to ld.lld to indicate
we want to use lld by default.