"Too many open files" error on tiering in Column shard

[swalrus1]

Column shard creates unlimited number of file descriptors to connect to S3 for reading evicted blobs. If number of opened file descriptors reach ulimit -n, either VERIFY fails or scans that touch evicted rows fail with error "cannot get blob: curlCode: 6, Couldn't resolve host name". On scenario test setup, one descriptor were opened for every blob evicted to S3.

Failed verify:

VERIFY failed (2024-08-26T08:33:20.336761Z): grpc failed accept4: Too many open files
  contrib/libs/grpc/src/core/lib/iomgr/tcp_server_posix.cc:349
  on_read(): requirement false failed
??+0 (0xACB90CD)
??+0 (0xACB2DF7)
??+0 (0x11AFF6F7)
??+0 (0x11A33481)
??+0 (0x11AF06D7)
??+0 (0x11AEE96B)
??+0 (0x11AFA953)
??+0 (0x11AE1168)
??+0 (0x11D6F6F0)
??+0 (0x1564C27E)
??+0 (0xBA3A809)
??+0 (0xBA3AAEA)
??+0 (0xACBD7DF)
??+0 (0x7FA649C36609)
clone+67 (0x7FA649B56353)

Reproduce by running tiering scenario test #8262 until eviction.