[bazel] Remove `linkshared = True` from bazel/test_external/long_command_line (#1715)

I'm not sure why this was originally added as part of #1373, but its
breaking with our transition to using true dynamic linking because bazel
currently does not know how to include PIC versions of the standard
libraries.

See #1714

bazel/test_external/long_command_line/BUILD.bazel

diff --git a/bazel/test_external/long_command_line/BUILD.bazel b/bazel/test_external/long_command_line/BUILD.bazel
index 29ede1f..e07fc4f 100644
--- a/bazel/test_external/long_command_line/BUILD.bazel
+++ b/bazel/test_external/long_command_line/BUILD.bazel
@@ -48,7 +48,6 @@
 cc_binary(
     name = "long_command_line",
     srcs = ["long_command_line.cc"],
-    linkshared = True,
     deps = [":{}_{}".format(target, suffix) for target in _TEST_TARGETS for suffix in _TEST_TARGET_SUFFIXES],
 )