Remove more remnants of PEAR installation support #1191

Job	Run time
Build Phar on PHP: 8.0	34s
Coverage: 5.4	18m 27s
Coverage: 7.2 with custom ini settings	4m 14s
Coverage: 8.3	3m 28s
PHP: 5.4	1m 3s
PHP: 5.5	4m 35s
PHP: 5.6	4m 55s
PHP: 7.0	1m 28s
PHP: 7.1	1m 18s
PHP: 7.2	1m 15s
PHP: 7.3	45s
PHP: 7.4	46s
PHP: 8.0	48s
PHP: 8.1	41s
PHP: 8.2	45s
PHP: 8.3	35s
PHP: 8.4	1m 34s
PHP: 5.5 with custom ini settings	3m 51s
PHP: 7.0 with custom ini settings	1m 6s
coveralls-finish	6s
	52m 14s

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