do not use stunnnel for testing on aarch64
    
    The test 1561 intermittently fails when upstream test-suite runs
    for the second time during the build:
    ```
     [ ] Initializing inetd mode configuration
     [ ] Clients allowed=500
     [.] stunnel 5.66 on aarch64-redhat-linux-gnu platform
     [.] Compiled/running with OpenSSL 3.0.5 5 Jul 2022
     [.] Threading:PTHREAD Sockets:POLL,IPv6 TLS:ENGINE,FIPS,OCSP,PSK,SNI
     [ ] errno: (*__errno_location ())
     [ ] Initializing inetd mode configuration
     [.] Reading configuration from file /builddir/build/BUILD/curl-7.87.0/build-full/tests/https_stunnel.conf
     [.] UTF-8 byte order mark not detected
     [.] FIPS mode disabled
     [ ] Compression disabled
     [ ] No PRNG seeding was required
     [ ] Initializing service [curltest]
     [ ] Using the default TLS version as specified in OpenSSL crypto policies. Not setting explicitly.
     [ ] Using the default TLS version as specified in OpenSSL crypto policies. Not setting explicitly
     [ ] stunnel default security level set: 2
     [ ] Ciphers: PROFILE=SYSTEM
     [ ] TLSv1.3 ciphersuites: TLS_AES_256_GCM_SHA384:TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256
     [ ] TLS options: 0x2100000 (+0x0, -0x0)
     [ ] Session resumption enabled
     [ ] Loading certificate from file: /builddir/build/BUILD/curl-7.87.0/tests/stunnel.pem
     [ ] Certificate loaded from file: /builddir/build/BUILD/curl-7.87.0/tests/stunnel.pem
     [ ] Loading private key from file: /builddir/build/BUILD/curl-7.87.0/tests/stunnel.pem
     [ ] Private key loaded from file: /builddir/build/BUILD/curl-7.87.0/tests/stunnel.pem
     [ ] Private key check succeeded
     [ ] DH initialization needed for DHE-RSA-AES256-GCM-SHA384
     [ ] DH initialization
     [ ] Could not load DH parameters from /builddir/build/BUILD/curl-7.87.0/tests/stunnel.pem
     [ ] Using dynamic DH parameters
     [ ] ECDH initialization
     [ ] ECDH initialized with curves X25519:P-256:X448:P-521:P-384
     [.] Configuration successful
     [ ] Deallocating deployed section defaults
     [ ] Binding service [curltest]
     [ ] Listening file descriptor created (FD=8)
     [ ] Setting accept socket options (FD=8)
     [ ] Option SO_REUSEADDR set on accept socket
     [.] Binding service [curltest] to 0.0.0.0:24847: Address already in use (98)
     [ ] Listening file descriptor created (FD=8)
     [ ] Setting accept socket options (FD=8)
     [ ] Option SO_REUSEADDR set on accept socket
     [.] Binding service [curltest] to :::24847: Address already in use (98)
     [!] Binding service [curltest] failed
     [ ] Unbinding service [curltest]
     [ ] Service [curltest] closed
     [ ] Deallocating deployed section defaults
     [ ] Deallocating section [curltest]
     [ ] Initializing inetd mode configuration
    ```