test: don't clobber $PATH

BATS depends on `$PATH` somehow and if not handled properly, modifying `$PATH` breaks BATS badly. But, it doesn't seem like we have any reason to modify `$PATH` in the first place...so don't.

test/svn: don't clobber `$PATH`
test/ruby: don't clobber `$PATH`
test/search: don't clobber `$PATH`

Author: gaelicWizard

test/lib/search.bats

@@ -7,7 +7,6 @@ function local_setup_file() {
 }
 
 function local_setup() {
-    export PATH="/usr/bin:/bin:/usr/sbin"
     # shellcheck disable=SC2034
     BASH_IT_SEARCH_USE_COLOR=false
 }

test/plugins/ruby.plugin.bats

@@ -6,10 +6,6 @@ function local_setup_file() {
   setup_libs "helpers"
 }
 
-function local_setup() {
-  export PATH="/usr/bin:/bin:/usr/sbin"
-}
-
 @test "plugins ruby: remove_gem is defined" {
   run load "${BASH_IT?}/plugins/available/ruby.plugin.bash"
   assert_success

test/themes/base.theme.svn.bats

@@ -24,7 +24,7 @@ function setup_svn_path {
   assert_file_exist "$svn_path/svn"
 
   # Make sure that the requested SVN script is on the path
-  export PATH="$svn_path:/usr/bin:/bin:/usr/sbin"
+  export PATH="$svn_path:$PATH"
 }
 
 @test 'themes base: SVN: detect SVN repo' {