GD-Logging: Change LOG_DEBUG to LOG_INFO

* Given that LOG_DEBUG will be disabled by default,
  changing existing LOG_DEBUG to LOG_INFO so that
  we don't lose these logs

Bug: 170163727
Test: atest bluetooth_test_gd, manual device test
Tag: #gd-refactor
Change-Id: I84db7751d4bbe6d3ea88122b8cdf72bc150fbe7a