Bug: Lexical applies table borders by default, even when the original source does not specify them

When table content is copied from excel wherein table doesn't have borders, still lexical editor adds borders by default.

Lexical version: 0.12.4

## Steps To Reproduce

1. Create table in excel without borders and copy its content

**Source:**

2. Paste table content in lexical playground, content shows borders which are not present in source.

**Lexical Playground destination:**

## The current behaviour

Table content has borders for each cell.

## The expected behaviour

Table content should not have borders for cells, similar to source of table.

## Impact of fix

The bug is consistently reproducible and has a significant impact on the user experience, as the end user sees data that differs from the source. Additionally, discrepancies arise in the report formatting when reports are generated.

Reproduce the issue by copying a borderless table from Excel into the Lexical Playground, then trace the paste handling for table content. Done means the pasted cells retain the source's lack of borders and the behavior is covered by an appropriate regression test.

Written by the indexing model from the issue text.