[CLEANUP] Avoid multiline strings in `OutputFormatTest` (#1429) #3993

Job	Run time
PHP Lint (8.1)	17s
PHP Lint (8.2)	21s
PHP Lint (7.3)	16s
PHP Lint (8.0)	25s
PHP Lint (8.4)	16s
PHP Lint (8.3)	18s
PHP Lint (7.4)	17s
PHP Lint (7.2)	17s
PHP Lint (8.5)	16s
Static Analysis (php:rector, 8.3)	35s
Static Analysis (php:stan, 8.3)	30s
Static Analysis (composer:normalize, 8.3)	19s
Static Analysis (php:fixer, 8.3)	27s
Unit tests (7.3)	17s
Unit tests (8.2)	24s
Unit tests (8.5)	20s
Unit tests (8.0)	20s
Unit tests (8.4)	24s
Unit tests (8.1)	18s
Unit tests (7.4)	18s
Unit tests (7.2)	21s
Unit tests (8.3)	12s
	7m 28s

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