The error message indicates that the Junos-http application is not defined, so you need to either create a custom application or modify the security policy to use the built-in Junos-http application.
Doing either of these will allow you to successfully commit the configuration.

Explanation
AppQoS is a service that allows you to prioritize and manage the quality of service (QoS) for different types of applications on SRX Series devices. AppQoS uses application signatures to identify and classify the traffic, and then applies QoS policies to assign bandwidth, priority, and scheduling parameters to the traffic. AppQoS can help you optimize the performance of critical applications, such as VoIP, and ensure that they get the required bandwidth and latency in a congested network12. In this scenario, you can use AppQoS to prioritize the VoIP traffic over other traffic and guarantee its QoS on the SRX Series device at the branch office. References:
Understanding Application Quality of Service
Configuring Application Quality of Service

The SSL proxy can detect if encryption is being used by looking at the destination port number of the packet. If the port number is 443, then the proxy can assume that the packet is being sent over an encrypted connection. If the port number is different, then the proxy can assume that the packet is not encrypted.
The SSL proxy is a security feature that provides visibility and control over SSL/TLS encrypted traffic. When SSL proxy is enabled, it intercepts SSL/TLS traffic and decrypts it to allow visibility into the content of the encrypted traffic. However, before decrypting the traffic, the SSL proxy must first determine if the traffic is encrypted.
To detect if encryption is being used, the SSL proxy looks at the destination port number. If the destination port number is a known SSL/TLS port (e.g., TCP port 443), the SSL proxy assumes that encryption is being used and intercepts the traffic. If the destination port is not a known SSL/TLS port, the SSL proxy does not intercept the traffic and allows it to pass through the device unmodified.

The Flow Collector can use statistical sampling to collect and store network flow data in the JSA database. The Event Collector collects information from various sources including syslog, SNMP, NetFlow, and BGP FlowSpec. Both the Flow Collector and the Event Collector parse logs to extract useful information from the logs.