Do not cancel context on Connection.Close (#40769) (#40776)

This commit removes a call to conn.cancelReqs() that causes the
Connection to be unusable after Close() is called, leading to the bug
described by #40705.

(cherry picked from commit b0e4f85)

Co-authored-by: Tiago Queiroz <tiago.queiroz@elastic.co>

libbeat/esleg/eslegclient/connection.go

@@ -326,7 +326,6 @@ func (conn *Connection) Ping() (ESPingData, error) {
 // Close closes a connection.
 func (conn *Connection) Close() error {
 	conn.HTTP.CloseIdleConnections()
-	conn.cancelReqs()
 	return nil
 }