[lldb][docs] Update reference to test directory location (#71081)

The instructions for running single tests in the LLDB test suite used an
older directory structure from before the LLVM project became a
monorepo. This commit updates the references to these directories.

Author: chelcassanova

lldb/docs/resources/test.rst

@@ -483,23 +483,23 @@ run as part of a test suite.
 
 ::
 
-   $ ./bin/llvm-lit -sv tools/lldb/test --filter <test>
+   $ ./bin/llvm-lit -sv <llvm-project-root>/lldb/test --filter <test>
 
 
 Because lit automatically scans a directory for tests, it's also possible to
 pass a subdirectory to run a specific subset of the tests.
 
 ::
 
-   $ ./bin/llvm-lit -sv tools/lldb/test/Shell/Commands/CommandScriptImmediateOutput
+   $ ./bin/llvm-lit -sv <llvm-project-root>/lldb/test/Shell/Commands/CommandScriptImmediateOutput
 
 
 For the SB API tests it is possible to forward arguments to ``dotest.py`` by
 passing ``--param`` to lit and setting a value for ``dotest-args``.
 
 ::
 
-   $ ./bin/llvm-lit -sv tools/lldb/test --param dotest-args='-C gcc'
+   $ ./bin/llvm-lit -sv <llvm-project-root>/lldb/test --param dotest-args='-C gcc'
 
 
 Below is an overview of running individual test in the unit and API test suites