Fix otel exporter otlp endpoint example value

[YonatanKiron]

Description

The environment variable default value should contain a prefix of http or https.
Once using an internal k8s value, the most common usage would be a http prefix

How Has This Been Tested?

Deployed the chart with and without the change;

• without the agent's failure to report data

Checklist:

• I have updated the relevant Helm chart(s) version(s) --> No need, it's docs change
• I have updated the relevant component changelog(s) --> No need, it's docs change
• This change does not affect any particular component (e.g. it's CI or docs change)

[CLAassistant]

All committers have signed the CLA.