Fix test_pkey_rsa.rb in FIPS. #1162

Job	Run time
openssl-1.0.2u	54s
openssl-1.1.0l	57s
openssl-1.1.1w	56s
openssl-3.0.14	56s
ruby-versions / Generate Ruby versions	1s
openssl-3.1.6	55s
openssl-3.2.2	54s
openssl-3.3.1	56s
openssl-master	3m 44s
libressl-3.1.5	54s
libressl-3.2.7	1m 1s
libressl-3.3.6	57s
libressl-3.4.3	59s
libressl-3.5.3	1m 4s
libressl-3.6.3	1m 4s
libressl-3.7.3	1m 0s
libressl-3.8.4	1m 2s
libressl-3.9.2	1m 1s
openssl-3.0.14 with fips provider	37s
openssl-3.1.6 with fips provider	42s
openssl-3.2.2 with fips provider	46s
openssl-3.3.1 with fips provider	43s
openssl-master with fips provider	3m 18s
openssl-3.3.1 without legacy provider	1m 2s
ubuntu-22.04 2.7	58s
ubuntu-22.04 3.0	52s
ubuntu-22.04 3.1	59s
ubuntu-22.04 3.2	59s
ubuntu-22.04 3.3	1m 7s
ubuntu-22.04 head	1m 0s
ubuntu-22.04 truffleruby	1m 31s
ubuntu-22.04 truffleruby-head	1m 39s
ubuntu-20.04 2.7	59s
ubuntu-20.04 3.0	56s
ubuntu-20.04 3.1	56s
ubuntu-20.04 3.2	55s
ubuntu-20.04 3.3	57s
ubuntu-20.04 head	54s
ubuntu-20.04 truffleruby	1m 36s
ubuntu-20.04 truffleruby-head	1m 48s
macos-latest 2.7	49s
macos-latest 3.0	42s
macos-latest 3.1	38s
macos-latest 3.2	41s
macos-latest 3.3	49s
macos-latest head	39s
macos-latest truffleruby	1m 0s
macos-latest truffleruby-head	57s
windows-latest 2.7	4m 27s
windows-latest 3.0	4m 38s
windows-latest 3.1	4m 19s
windows-latest 3.2	4m 48s
windows-latest 3.3	5m 49s
windows-latest head	4m 4s
windows-latest ucrt	3m 41s
windows-latest mswin	3m 11s
	1h 25m 41s

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