fix: increase loop iteration count in pid lookup

[arthur-zhang]

Description

the process level is bigger than 4 in container like envs. If we start tetragon late after my process start, process may miss some parent process.

For example, in the popular orbstack(https://orbstack.dev/) implementation. Starting from the current process to the root process with pid 1, it takes 5 steps. Change the loop count to a higher value make tetragon work in orbstack vms. Or Tetragon will find parent failed, and affect many functions.

zsh-79260   [007] ....1 80569.428901: bpf_trace_printk: >>>>__event_find_parent: fork, pid=28997, value is null:1
 zsh-79260   [007] ....1 80569.428901: bpf_trace_printk: >>>>__event_find_parent: fork, pid=544, value is null:1
 zsh-79260   [007] ....1 80569.428902: bpf_trace_printk: >>>>__event_find_parent: fork, pid=508, value is null:1
 zsh-79260   [007] ....1 80569.428902: bpf_trace_printk: >>>>__event_find_parent: fork, pid=507, value is null:1
 zsh-79260   [007] ....1 80569.428902: bpf_trace_printk: >>>>__event_find_parent: fork, pid=1, value is null:0

Changelog

increase loop iteration count in event_find_curr function from 4 to 6