removing incorrect CORS headers

[DenysGonchar]

There are multiple things that are wrong with that admin API Access-Control-Allow-* headers, also we do not support it for GraphQL nor client REST API.

Removing them for now, if we want to add CORS support in the future it must be done properly and for GraphQL and
client REST API as well admin REST API.

Issue can be easily demonstrated with curl, below is the corresponding part of the config:

[[listen.http]]
  port = 8088
  transport.num_acceptors = 10
  transport.max_connections = 1024
  tls.verify_mode = "none"
  tls.certfile = "priv/ssl/fake_cert.pem"
  tls.keyfile = "priv/ssl/fake_key.pem"
  
  [[listen.http.handlers.mongoose_admin_api]]
    host = "_"
    path = "/api"

and here are 2 curl commands:

• HTTP1.1 request: curl -v --http1.1 --insecure -X OPTIONS https://localhost:8088/api/users/localhost
• HTTP2 request: curl -v --http2 --insecure -X OPTIONS https://localhost:8088/api/users/localhost

Notice that HTTP2 query fails with existing CORS headers.

[mongoose-im]

small_tests_24 / small_tests / 6732535
Reports root / small

---

small_tests_25 / small_tests / 6732535
Reports root / small

---

small_tests_25_arm64 / small_tests / 6732535
Reports root / small

---

ldap_mnesia_24 / ldap_mnesia / 6732535
Reports root/ big
OK: 2219 / Failed: 0 / User-skipped: 827 / Auto-skipped: 0

---

dynamic_domains_pgsql_mnesia_24 / pgsql_mnesia / 6732535
Reports root/ big
OK: 4180 / Failed: 0 / User-skipped: 88 / Auto-skipped: 0

---

ldap_mnesia_25 / ldap_mnesia / 6732535
Reports root/ big
OK: 2219 / Failed: 0 / User-skipped: 827 / Auto-skipped: 0

---

dynamic_domains_pgsql_mnesia_25 / pgsql_mnesia / 6732535
Reports root/ big
OK: 4180 / Failed: 0 / User-skipped: 88 / Auto-skipped: 0

---

pgsql_mnesia_24 / pgsql_mnesia / 6732535
Reports root/ big
OK: 4553 / Failed: 0 / User-skipped: 97 / Auto-skipped: 0

---

dynamic_domains_mysql_redis_25 / mysql_redis / 6732535
Reports root/ big
OK: 4154 / Failed: 0 / User-skipped: 114 / Auto-skipped: 0

---

dynamic_domains_mssql_mnesia_25 / odbc_mssql_mnesia / 6732535
Reports root/ big
OK: 4177 / Failed: 0 / User-skipped: 91 / Auto-skipped: 0

---

internal_mnesia_25 / internal_mnesia / 6732535
Reports root/ big
OK: 2361 / Failed: 0 / User-skipped: 685 / Auto-skipped: 0

---

elasticsearch_and_cassandra_25 / elasticsearch_and_cassandra_mnesia / 6732535
Reports root/ big
OK: 2721 / Failed: 0 / User-skipped: 664 / Auto-skipped: 0

---

mysql_redis_25 / mysql_redis / 6732535
Reports root/ big
OK: 4539 / Failed: 0 / User-skipped: 111 / Auto-skipped: 0

---

mssql_mnesia_25 / odbc_mssql_mnesia / 6732535
Reports root/ big
OK: 4550 / Failed: 0 / User-skipped: 100 / Auto-skipped: 0

---

pgsql_mnesia_25 / pgsql_mnesia / 6732535
Reports root/ big
OK: 4553 / Failed: 0 / User-skipped: 97 / Auto-skipped: 0

[arcusfelis]

ok