Fix the default bash HISTFILE changing to .sh_history instead of .bash_history

Fixes #4765

shell-integration/bash/kitty.bash

@@ -41,6 +41,11 @@ _ksi_main() {
             _ksi_safe_source "$KITTY_BASH_POSIX_ENV" && builtin export ENV="$KITTY_BASH_POSIX_ENV";
         else
             builtin set +o posix;
+            if [[ -n "$KITTY_BASH_UNEXPORT_HISTFILE" ]]; then
+                export -n HISTFILE;
+                unset KITTY_BASH_UNEXPORT_HISTFILE;
+            fi
+
             # See run_startup_files() in shell.c in the Bash source code
             if builtin shopt -q login_shell; then
                 if [[ "$KITTY_BASH_INJECT" != *"no-profile"* ]]; then