NH-64310: remove the logic that set obfuscate for db from sw side

[xuan-cao-swi]

Description

As open-telemetry/opentelemetry-ruby-contrib#682 merged, no need this logic so remove them. Although, for RUBY 2.7, still need to manual set the obfuscate for instrumentation if needed.

e.g.

SolarWindsAPM::OTelConfig.initialize_with_config do |config|
  config["OpenTelemetry::Instrumentation::Dalli"] = {db_statement: :obfuscate}
  config["OpenTelemetry::Instrumentation::Mysql2"] = {db_statement: :obfuscate}
  config["OpenTelemetry::Instrumentation::PG"] = {db_statement: :obfuscate}
end

[cheempz]

LGTM, thanks @xuan-cao-swi!