Revert "tests: Add a test that 'rehash' isn't run."

This reverts commit 62c5575848.

The test fails when zsh/parameter is available.

highlighters/main/test-data/no-rehash.zsh

@@ -1,39 +0,0 @@
-# -------------------------------------------------------------------------------------------------
-# Copyright (c) 2020 zsh-syntax-highlighting contributors
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without modification, are permitted
-# provided that the following conditions are met:
-#
-#  * Redistributions of source code must retain the above copyright notice, this list of conditions
-#    and the following disclaimer.
-#  * Redistributions in binary form must reproduce the above copyright notice, this list of
-#    conditions and the following disclaimer in the documentation and/or other materials provided
-#    with the distribution.
-#  * Neither the name of the zsh-syntax-highlighting contributors nor the names of its contributors
-#    may be used to endorse or promote products derived from this software without specific prior
-#    written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
-# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
-# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
-# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
-# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
-# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-# -------------------------------------------------------------------------------------------------
-# -*- mode: zsh; sh-indentation: 2; indent-tabs-mode: nil; sh-basic-offset: 2; -*-
-# vim: ft=zsh sw=2 ts=2 et
-# -------------------------------------------------------------------------------------------------
-
-hash zsyh-hashed-command=/usr/bin/env
-BUFFER='doesnotexist; zsyh-hashed-command'
-
-# Test that highlighting "doesnotexist" does not invoke the "rehash" builtin,
-# which would delete hashed commands (such as "zsyh-hashed-command").
-expected_region_highlight=(
-  "1 12 unknown-token"     # doesnotexist
-  "13 13 commandseparator" # ;
-  "15 33 hashed-command"   # zsyh-hashed-command
-)