Apply Strength of Blood PDR only while leeching

[Nerotox]

Fixes #7764

Description of the problem being solved:

Strength of Blood Physical Damage Reduction was applying even if not leeching / having no leech sources.

Steps taken to verify a working solution:

• Make a PoB without leech
• Add a legion jewel with strength of blood
• PDR should not be applied.
• Add leech
• PDR should be applied now.

Link to a build that showcases this PR:

https://pobb.in/TVCpOHP366PS (Strength of blood unselected, gave PDR in tooltip before)

Before screenshot:

After screenshot: