List of ref. des. in each BOM line created using bom_csv_grouped_by_value_with_fp ends with trailing comma and whitespace

Description

The output result from BOM script bom_csv_grouped_by_value_with_fp generates extra trailing comma and whitespace in each column of reference designators.

Steps to reproduce

View the second sheet in this document https://docs.google.com/spreadsheets/d/1-iC-RxhmScL3geooAIgv6dD6j5uFJ_zHekPzkbhhtWs/edit?usp=sharing

1. Generate BOM from schematic editor using script bom_csv_grouped_by_value_with_fp
2. See for example this line: J11, J12, J13, J14,
3. The fourth comma and whitespace should be removed

KiCad Version

Application: KiCad (64-bit)

Version: (6.0.1), release build

Libraries:
	wxWidgets 3.1.5
	libcurl/7.78.0-DEV Schannel zlib/1.2.11

Platform: Windows 10 (build 19043), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
	Date: Jan 15 2022 13:36:27
	wxWidgets: 3.1.5 (wchar_t,wx containers)
	Boost: 1.76.0
	OCC: 7.5.0
	Curl: 7.78.0-DEV
	ngspice: 35
	Compiler: Visual C++ 1929 without C++ ABI

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON