[configtls] Use configtls.NewDefaultClientConfig instead of manually creating struct

[mackjmr]

Describe the issue you're reporting

Move away from manually creating configtls.ClientConfig in favor of using configtls.NewDefaultClientConfig.

This is necessary for the following components:

• [ ] config/configgrpc
• [ ] config/confighttp
• [ ] exporter/otlpexporter
• [ ] exporter/otlphttpexporter
• [ ] internal/e2e

[wasim-nihal]

Hello @mackjmr ! Is this open for contribution?

[mackjmr]

Hi @wasim-nihal, yes this is open for contributions! I've listed in the issue descriptions the components in which this needs to be changed, please link the PRs when you open them similarely to what is done in https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/35457 🙂