eshell: Remove binding to obsolete function eshell-bol

[mychris]

eshell-bol is an obsolete function starting with Emacs 30.1. See (view-emacs-news 30.1):

*** Eshell now uses 'field' properties in its output.
In particular, this means that pressing the '<home>' key moves the
point to the beginning of your input, not the beginning of the whole
line. If you want to go back to the old behavior, add something like
this to your configuration:

(keymap-set eshell-mode-map "<home>" #'eshell-bol-ignoring-prompt)

This also means you no longer need to adjust 'eshell-prompt-regexp'
when customizing your Eshell prompt.

With this change in eshell, evil-beginning-of-line already moves to the end of the prompt, if there is any. The only difference which might be there is that if the cursor is in column zero of a line which has a prompt, it doesn't move to the end of the prompt, which I think was the old behaviour of eshell-bol. But since eshell-bol is now a function alias to beginning-of-line, it doesn't make any difference if the mapping in evil-collection is present or not.

Currently, the mapping generates a warning on the first usage of eshell-bol.

[condy0919]

I think we can remove these old bindings, keep the behavior same with Emacs master.