[Keyboard] Helix use `post_rules.mk` (#14216)

* Helix/pico use post_rules.mk insted of local_features.mk

Tested with the following procedure.
```
git checkout 77a93fec79 (qmk/develop)
make clean
make helix/pico:all:check-md5
make helix/pico/sc:all:check-md5
git checkout helix_use_post_rules.mk
make clean
make helix/pico:all:check-md5
make helix/pico/sc:all:check-md5
```

* Helix/rev2 use post_rules.mk

Tested with the following procedure.
```
git checkout 77a93fec79 (qmk/develop)
make clean
make helix/pico:all:check-md5
make helix/pico/sc:all:check-md5
make helix/rev2:all:check-md5
make helix/rev2/sc:all:check-md5
git checkout helix_use_post_rules.mk
make clean
make helix/pico:all:check-md5
make helix/pico/sc:all:check-md5
make helix/rev2:all:check-md5
make helix/rev2/sc:all:check-md5
```

5 files changed, 1 insertions, 17 deletions

diff --git a/keyboards/helix/pico/keymaps/biacco/rules.mk b/keyboards/helix/pico/keymaps/biacco/rules.mk
index 37e49977c..993ade267 100644
--- a/keyboards/helix/pico/keymaps/biacco/rules.mk
+++ b/keyboards/helix/pico/keymaps/biacco/rules.mk
@@ -18,7 +18,3 @@ LTO_ENABLE = no  # if firmware size over limit, try this option
 # LED_UNDERGLOW_ENABLE = no   # LED underglow (Enable WS2812 RGB underlight.)
 LED_ANIMATIONS = no           # LED animations
 # IOS_DEVICE_ENABLE = no      # connect to IOS device (iPad,iPhone)
-
-# convert Helix-specific options (that represent combinations of standard options)
-#   into QMK standard options.
-include $(strip $(KEYBOARD_LOCAL_FEATURES_MK))
diff --git a/keyboards/helix/pico/keymaps/default/rules.mk b/keyboards/helix/pico/keymaps/default/rules.mk
index 8f198e380..8977897f9 100644
--- a/keyboards/helix/pico/keymaps/default/rules.mk
+++ b/keyboards/helix/pico/keymaps/default/rules.mk
@@ -18,7 +18,3 @@ LTO_ENABLE = no  # if firmware size over limit, try this option
 # LED_UNDERGLOW_ENABLE = no   # LED underglow (Enable WS2812 RGB underlight.)
 # LED_ANIMATIONS = yes        # LED animations
 # IOS_DEVICE_ENABLE = no      # connect to IOS device (iPad,iPhone)
-
-# convert Helix-specific options (that represent combinations of standard options)
-#   into QMK standard options.
-include $(strip $(KEYBOARD_LOCAL_FEATURES_MK))
diff --git a/keyboards/helix/pico/keymaps/mtei/rules.mk b/keyboards/helix/pico/keymaps/mtei/rules.mk
index 165233f5f..05a60f67d 100644
--- a/keyboards/helix/pico/keymaps/mtei/rules.mk
+++ b/keyboards/helix/pico/keymaps/mtei/rules.mk
@@ -18,7 +18,3 @@ LTO_ENABLE = no  # if firmware size over limit, try this option
 # LED_UNDERGLOW_ENABLE = no   # LED underglow (Enable WS2812 RGB underlight.)
 # LED_ANIMATIONS = yes        # LED animations
 # IOS_DEVICE_ENABLE = no      # connect to IOS device (iPad,iPhone)
-
-# convert Helix-specific options (that represent combinations of standard options)
-#   into QMK standard options.
-include $(strip $(KEYBOARD_LOCAL_FEATURES_MK))
diff --git a/keyboards/helix/pico/local_features.mk b/keyboards/helix/pico/post_rules.mk
index be5c739f9..38573d75a 100644
--- a/keyboards/helix/pico/local_features.mk
+++ b/keyboards/helix/pico/post_rules.mk
@@ -1,12 +1,10 @@
 #
-#  local_features.mk contains post-processing rules for the Helix keyboard.
+#  post_rules.mk contains post-processing rules for the Helix keyboard.
 #
 #   Post-processing rules convert keyboard-specific shortcuts (that represent
 #   combinations of standard options) into QMK standard options.
 #
 
-KEYBOARD_LOCAL_FEATURES_MK :=
-
 define HELIX_CUSTOMISE_MSG
   $(info Helix Spacific Build Options)
   $(info -  OLED_ENABLE          = $(OLED_ENABLE))
diff --git a/keyboards/helix/pico/rules.mk b/keyboards/helix/pico/rules.mk
index cb9a70e00..12caec37e 100644
--- a/keyboards/helix/pico/rules.mk
+++ b/keyboards/helix/pico/rules.mk
@@ -1,5 +1,3 @@
-KEYBOARD_LOCAL_FEATURES_MK := $(dir $(lastword $(MAKEFILE_LIST)))local_features.mk
-
 # Helix Spacific Build Options default values
 OLED_ENABLE = no            # OLED_ENABLE
 LOCAL_GLCDFONT = no         # use each keymaps "helixfont.h" insted of "common/glcdfont.c"