bug(secret): set limit for line length

[DmitriyLewen]

Description

We show line with secret (also line before and after it) in report. But there are cases when this line is very long (see #6980). In this case we will show very large output.

So we need to set maximum line length for secrets or set limit on output shown.

Discussed in https://github.com/aquasecurity/trivy/discussions/6980