autotest: stop emitting duplicate rangefinder headings

[peterbarker]

This was only an issue for the Wasp rangefinder block, which drops stuff
in at the top level by specifying the same subgroup name as the top
level.

[peterbarker]

Closes #12014

[peterbarker]

This was tested by running the current code's build_parameters.sh, moving the output aside, running the new code's build_parameters.sh, then running diff -ur on the results and inspecting that output.

[peterbarker]

diff -ur Parameters/ArduCopter/apm.pdef.xml Parameters-new/ArduCopter/apm.pdef.xml
--- Parameters/ArduCopter/apm.pdef.xml  2020-06-01 17:28:07.189641439 +1000
+++ Parameters-new/ArduCopter/apm.pdef.xml      2020-06-01 17:27:25.124493046 +1000
@@ -10993,8 +10993,6 @@
 <value code=" 25">Down</value>
 </values>
 </param>
-</parameters>
-<parameters name="RNGFND1_">
 <param humanName="Moving Average Range" name="RNGFND1_WSP_MAVG" documentation="Sets the number of historic range results to use for calculating the current range result. When MAVG is greater than 1, the current range result will be the current measured value averaged with the N-1 previous results" user="Advanced">
 <field name="Range">0 255</field>
 </param>
@@ -11161,8 +11159,6 @@
 <value code=" 25">Down</value>
 </values>
 </param>
-</parameters>
-<parameters name="RNGFND2_">
 <param humanName="Moving Average Range" name="RNGFND2_WSP_MAVG" documentation="Sets the number of historic range results to use for calculating the current range result. When MAVG is greater than 1, the current range result will be the current measured value averaged with the N-1 previous results" user="Advanced">
 <field name="Range">0 255</field>
 </param>
@@ -11329,8 +11325,6 @@
 <value code=" 25">Down</value>
 </values>
 </param>
-</parameters>
-<parameters name="RNGFND3_">
 <param humanName="Moving Average Range" name="RNGFND3_WSP_MAVG" documentation="Sets the number of historic range results to use for calculating the current range result. When MAVG is greater than 1, the current range result will be the current measured value averaged with the N-1 previous results" user="Advanced">
 <field name="Range">0 255</field>
 </param>
@@ -11497,8 +11491,6 @@
 <value code=" 25">Down</value>
 </values>

[peterbarker]

diff -ur Parameters/ArduCopter/Parameters.rst Parameters-new/ArduCopter/Parameters.rst
--- Parameters/ArduCopter/Parameters.rst        2020-06-01 17:28:07.189641439 +1000
+++ Parameters-new/ArduCopter/Parameters.rst    2020-06-01 17:27:25.124493046 +1000
@@ -41004,13 +41004,6 @@
 
 
 
-
-.. _parameters_RNGFND1_:
-
-RNGFND1\_ Parameters
---------------------
-
-
 .. _RNGFND1_WSP_MAVG:
 
 RNGFND1\_WSP\_MAVG: Moving Average Range
@@ -41581,13 +41574,6 @@
 
 
 
-
-.. _parameters_RNGFND2_:
-
-RNGFND2\_ Parameters
---------------------
-
-
 .. _RNGFND2_WSP_MAVG: