debugging: move the perf record part in application profiling since it is used in lab

[clementleger]

perf record is used directly in the application profiling labs so it should be presented in the application profiling slides

[Tropicao]

The issue should likely be taken the other way around:

• perf is currently first introduced in application tracing slides
• perf is introduced here because we are introducing uprobes for userspace uprobes
• removing it from here would either makes us remove uprobes, or use another tool to manipulate uprobes (uprobe script from perf-tools, raw tracefs read/writes). Both are unsatisfying solutions
• the better solution is likely to introduce a proper perf lab right in tracing labs to start exercising perf. Then perf usage in other labs should be a continuation on perf learning