Remove not needed ARGS from Dockerfile to reduce amount of Docker layers.

Thanks to folhabranca !

Closes #2301

Dockerfile

@@ -1,100 +1,6 @@
 FROM ubuntu:cosmic
 LABEL maintainer="wekan"
 
-# Declare Arguments
-ARG DEBUG
-ARG NODE_VERSION
-ARG METEOR_RELEASE
-ARG METEOR_EDGE
-ARG USE_EDGE
-ARG NPM_VERSION
-ARG FIBERS_VERSION
-ARG ARCHITECTURE
-ARG SRC_PATH
-ARG WITH_API
-ARG ACCOUNTS_LOCKOUT_KNOWN_USERS_FAILURES_BEFORE
-ARG ACCOUNTS_LOCKOUT_KNOWN_USERS_PERIOD
-ARG ACCOUNTS_LOCKOUT_KNOWN_USERS_FAILURE_WINDOW
-ARG ACCOUNTS_LOCKOUT_UNKNOWN_USERS_FAILURES_BERORE
-ARG ACCOUNTS_LOCKOUT_UNKNOWN_USERS_LOCKOUT_PERIOD
-ARG ACCOUNTS_LOCKOUT_UNKNOWN_USERS_FAILURE_WINDOW
-ARG EMAIL_NOTIFICATION_TIMEOUT
-ARG MATOMO_ADDRESS
-ARG MATOMO_SITE_ID
-ARG MATOMO_DO_NOT_TRACK
-ARG MATOMO_WITH_USERNAME
-ARG BROWSER_POLICY_ENABLED
-ARG TRUSTED_URL
-ARG WEBHOOKS_ATTRIBUTES
-ARG OAUTH2_ENABLED
-ARG OAUTH2_LOGIN_STYLE
-ARG OAUTH2_CLIENT_ID
-ARG OAUTH2_SECRET
-ARG OAUTH2_SERVER_URL
-ARG OAUTH2_AUTH_ENDPOINT
-ARG OAUTH2_USERINFO_ENDPOINT
-ARG OAUTH2_TOKEN_ENDPOINT
-ARG OAUTH2_ID_MAP
-ARG OAUTH2_USERNAME_MAP
-ARG OAUTH2_FULLNAME_MAP
-ARG OAUTH2_EMAIL_MAP
-ARG LDAP_ENABLE
-ARG LDAP_PORT
-ARG LDAP_HOST
-ARG LDAP_BASEDN
-ARG LDAP_LOGIN_FALLBACK
-ARG LDAP_RECONNECT
-ARG LDAP_TIMEOUT
-ARG LDAP_IDLE_TIMEOUT
-ARG LDAP_CONNECT_TIMEOUT
-ARG LDAP_AUTHENTIFICATION
-ARG LDAP_AUTHENTIFICATION_USERDN
-ARG LDAP_AUTHENTIFICATION_PASSWORD
-ARG LDAP_LOG_ENABLED
-ARG LDAP_BACKGROUND_SYNC
-ARG LDAP_BACKGROUND_SYNC_INTERVAL
-ARG LDAP_BACKGROUND_SYNC_KEEP_EXISTANT_USERS_UPDATED
-ARG LDAP_BACKGROUND_SYNC_IMPORT_NEW_USERS
-ARG LDAP_ENCRYPTION
-ARG LDAP_CA_CERT
-ARG LDAP_REJECT_UNAUTHORIZED
-ARG LDAP_USER_SEARCH_FILTER
-ARG LDAP_USER_SEARCH_SCOPE
-ARG LDAP_USER_SEARCH_FIELD
-ARG LDAP_SEARCH_PAGE_SIZE
-ARG LDAP_SEARCH_SIZE_LIMIT
-ARG LDAP_GROUP_FILTER_ENABLE
-ARG LDAP_GROUP_FILTER_OBJECTCLASS
-ARG LDAP_GROUP_FILTER_GROUP_ID_ATTRIBUTE
-ARG LDAP_GROUP_FILTER_GROUP_MEMBER_ATTRIBUTE
-ARG LDAP_GROUP_FILTER_GROUP_MEMBER_FORMAT
-ARG LDAP_GROUP_FILTER_GROUP_NAME
-ARG LDAP_UNIQUE_IDENTIFIER_FIELD
-ARG LDAP_UTF8_NAMES_SLUGIFY
-ARG LDAP_USERNAME_FIELD
-ARG LDAP_FULLNAME_FIELD
-ARG LDAP_EMAIL_FIELD
-ARG LDAP_EMAIL_MATCH_ENABLE
-ARG LDAP_EMAIL_MATCH_REQUIRE
-ARG LDAP_EMAIL_MATCH_VERIFIED
-ARG LDAP_MERGE_EXISTING_USERS
-ARG LDAP_SYNC_USER_DATA
-ARG LDAP_SYNC_USER_DATA_FIELDMAP
-ARG LDAP_SYNC_GROUP_ROLES
-ARG LDAP_DEFAULT_DOMAIN
-ARG LDAP_SYNC_ADMIN_STATUS
-ARG LDAP_SYNC_ADMIN_GROUPS
-ARG HEADER_LOGIN_ID
-ARG HEADER_LOGIN_FIRSTNAME
-ARG HEADER_LOGIN_LASTNAME
-ARG HEADER_LOGIN_EMAIL
-ARG LOGOUT_WITH_TIMER
-ARG LOGOUT_IN
-ARG LOGOUT_ON_HOURS
-ARG LOGOUT_ON_MINUTES
-ARG CORS
-ARG DEFAULT_AUTHENTICATION_METHOD
-
 # Set the environment variables (defaults where required)
 # DOES NOT WORK: paxctl fix for alpine linux: https://github.com/wekan/wekan/issues/1303
 # ENV BUILD_DEPS="paxctl"