Allow to define _UNSECURED_ENV_VARIABLES for specific linters

[nvuillam]

Fixes #2699

[github-actions]

🦙 MegaLinter status: ⚠️ WARNING

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ BASH	bash-exec	5		0	0.01s
✅ BASH	shellcheck	5		0	0.09s
✅ BASH	shfmt	5	0	0	0.38s
✅ COPYPASTE	jscpd	yes		no	3.76s
✅ DOCKERFILE	hadolint	117		0	16.16s
✅ JSON	eslint-plugin-jsonc	23	0	0	2.24s
✅ JSON	jsonlint	21		0	0.19s
✅ JSON	v8r	23		0	13.86s
⚠️ MARKDOWN	markdownlint	249	0	252	6.71s
✅ MARKDOWN	markdown-link-check	249		0	5.37s
✅ MARKDOWN	markdown-table-formatter	249	0	0	23.94s
✅ OPENAPI	spectral	1		0	1.29s
⚠️ PYTHON	bandit	188		58	2.15s
✅ PYTHON	black	188	0	0	5.05s
✅ PYTHON	flake8	188		0	1.94s
✅ PYTHON	isort	188	0	0	0.75s
✅ PYTHON	mypy	188		0	7.31s
✅ PYTHON	pylint	188		0	13.21s
⚠️ PYTHON	pyright	188		303	18.72s
✅ PYTHON	ruff	188	0	0	0.45s
✅ REPOSITORY	checkov	yes		no	31.53s
✅ REPOSITORY	git_diff	yes		no	0.35s
✅ REPOSITORY	secretlint	yes		no	15.78s
✅ REPOSITORY	trivy	yes		no	26.03s
✅ SPELL	cspell	635		0	23.74s
⚠️ SPELL	vale	241		67	28.21s
✅ XML	xmllint	3	0	0	0.36s
✅ YAML	prettier	157	0	0	4.15s
✅ YAML	v8r	99		0	128.15s
✅ YAML	yamllint	158		0	1.43s

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