Bug 32659: Remove IPv6 address of default bridge.

The default bridge CDF2E852BF539B82BD10E27E9115A31734E378C2 has both an
IPv4 and IPv6 address but it is no longer reachable over it's IPv6
address, so it's time to remove it.

This fixes <https://bugs.torproject.org/32659>.

service/src/main/assets/common/bridges.txt

 obfs4 192.95.36.142:443 CDF2E852BF539B82BD10E27E9115A31734E378C2 cert=qUVQ0srL1JI/vO6V6m/24anYXiJD3QP2HgzUKQtQ7GRqqUvs7P+tG43RtAqdhLOALP7DJQ iat-mode=1
 obfs4 38.229.1.78:80 C8CBDB2464FC9804A69531437BCF2BE31FDD2EE4 cert=Hmyfd2ev46gGY7NoVxA9ngrPF2zCZtzskRTzoWXbxNkzeVnGFPWmrTtILRyqCTjHR+s9dg iat-mode=1
-obfs4 [2001:470:b381:bfff:216:3eff:fe23:d6c3]:443 CDF2E852BF539B82BD10E27E9115A31734E378C2 cert=qUVQ0srL1JI/vO6V6m/24anYXiJD3QP2HgzUKQtQ7GRqqUvs7P+tG43RtAqdhLOALP7DJQ iat-mode=1
 obfs4 37.218.240.34:40035 88CD36D45A35271963EF82E511C8827A24730913 cert=eGXYfWODcgqIdPJ+rRupg4GGvVGfh25FWaIXZkit206OSngsp7GAIiGIXOJJROMxEqFKJg iat-mode=1
 obfs4 37.218.245.14:38224 D9A82D2F9C2F65A18407B1D2B764F130847F8B5D cert=bjRaMrr1BRiAW8IE9U5z27fQaYgOhX1UCmOpg2pFpoMvo6ZgQMzLsaTzzQNTlm7hNcb+Sg iat-mode=0
 obfs4 85.31.186.98:443 011F2599C0E9B27EE74B353155E244813763C3E5 cert=ayq0XzCwhpdysn5o0EyDUbmSOx3X/oTEbzDMvczHOdBJKlvIdHHLJGkZARtT4dcBFArPPg iat-mode=0