Let latex writer line trimming from depart_entry() work as before #8781

This is cosmetic as the blank line starting varwidth environment used
for merged table cells in latex output changed nothing to PDF.

Nevertheless I extended a unit test to have a multi-paragraph merged
cell using varwidth. What is important is that \sphinxAtStartPar line
itself is never followed by blank line.

tests/roots/test-latex-table/complex.rst

@@ -11,9 +11,9 @@ grid table
 +---------+         +---------+
 | cell2-1 |         | cell2-3 |
 +         +---------+---------+
-|         | cell3-2           |
+|         | cell3-2-par1      |
 +---------+                   |
-| cell4-1 |                   |
+| cell4-1 | cell3-2-par2      |
 +---------+---------+---------+
 | cell5-1                     |
 +---------+---------+---------+

tests/roots/test-latex-table/expects/complex_spanning_cell.tex

@@ -19,7 +19,6 @@ consecutive multirow at end of row (1\sphinxhyphen{}4 and 1\sphinxhyphen{}5)
 \hline
 \sphinxmultirow{3}{1}{%
 \begin{varwidth}[t]{\sphinxcolwidth{1}{5}}
-
 \sphinxAtStartPar
 cell1\sphinxhyphen{}1
 \par
@@ -27,7 +26,6 @@ cell1\sphinxhyphen{}1
 }%
 &\sphinxmultirow{3}{2}{%
 \begin{varwidth}[t]{\sphinxcolwidth{1}{5}}
-
 \sphinxAtStartPar
 cell1\sphinxhyphen{}2
 \par
@@ -38,7 +36,6 @@ cell1\sphinxhyphen{}2
 cell1\sphinxhyphen{}3
 &\sphinxmultirow{3}{4}{%
 \begin{varwidth}[t]{\sphinxcolwidth{1}{5}}
-
 \sphinxAtStartPar
 cell1\sphinxhyphen{}4
 \par
@@ -46,7 +43,6 @@ cell1\sphinxhyphen{}4
 }%
 &\sphinxmultirow{2}{5}{%
 \begin{varwidth}[t]{\sphinxcolwidth{1}{5}}
-
 \sphinxAtStartPar
 cell1\sphinxhyphen{}5
 \par
@@ -55,7 +51,6 @@ cell1\sphinxhyphen{}5
 \\
 \cline{3-3}\sphinxtablestrut{1}&\sphinxtablestrut{2}&\sphinxmultirow{2}{6}{%
 \begin{varwidth}[t]{\sphinxcolwidth{1}{5}}
-
 \sphinxAtStartPar
 cell2\sphinxhyphen{}3
 \par

tests/roots/test-latex-table/expects/gridtable.tex

@@ -19,7 +19,6 @@ header3
 cell1\sphinxhyphen{}1
 &\sphinxmultirow{2}{5}{%
 \begin{varwidth}[t]{\sphinxcolwidth{1}{3}}
-
 \sphinxAtStartPar
 cell1\sphinxhyphen{}2
 \par
@@ -31,7 +30,6 @@ cell1\sphinxhyphen{}3
 \\
 \cline{1-1}\cline{3-3}\sphinxmultirow{2}{7}{%
 \begin{varwidth}[t]{\sphinxcolwidth{1}{3}}
-
 \sphinxAtStartPar
 cell2\sphinxhyphen{}1
 \par
@@ -44,9 +42,11 @@ cell2\sphinxhyphen{}3
 \cline{2-3}\sphinxtablestrut{7}&\sphinxstartmulticolumn{2}%
 \sphinxmultirow{2}{9}{%
 \begin{varwidth}[t]{\sphinxcolwidth{2}{3}}
+\sphinxAtStartPar
+cell3\sphinxhyphen{}2\sphinxhyphen{}par1
 
 \sphinxAtStartPar
-cell3\sphinxhyphen{}2
+cell3\sphinxhyphen{}2\sphinxhyphen{}par2
 \par
 \vskip-\baselineskip\vbox{\hbox{\strut}}\end{varwidth}%
 }%
@@ -58,7 +58,6 @@ cell4\sphinxhyphen{}1
 &\multicolumn{2}{l|}{\sphinxtablestrut{9}}\\
 \hline\sphinxstartmulticolumn{3}%
 \begin{varwidth}[t]{\sphinxcolwidth{3}{3}}
-
 \sphinxAtStartPar
 cell5\sphinxhyphen{}1
 \par