[LLDB] Fix timeout value on expect_gdbremote_sequence

D83904 seems to have changed timeout value on expect_gdbremote_sequence which
was 120 previously. This seems to be causing intermittent failures on
lldb-aarch64-ubuntu buildbot.

This patch fixes the timeout value to see the impact on test suite.

Example:
http://lab.llvm.org:8011/builders/lldb-aarch64-ubuntu/builds/7401/steps/test/logs/stdio

Differential Revision: https://reviews.llvm.org/D85514